comments (not for humans)
After working on retire.js I decided to take it for a real test run. I setup a node script with phantomjs and scanned the landing page of 150,000 Norwegian domains. These are the results. You will find that a lot of sites are using really old versions of libraries with known vulnerabilities (red means the library has known vulnerabilities). I think this supports the idea that most sites have the jQuery version that was available when the site was first made. Oh, and using a vulnerable library does not necessarily mean the site is vulnerable, but it might be.

Updated 8th of February, 2014:

jQuery

jQuery is a very widely used library. I was surprised however to find so many different and old versions in use

jquery 0.0.2
1
jquery 1-1.3.2
2
jquery 1.0
2
jquery 1.0.2
2
jquery 1.1
43
jquery 1.1.1
5
jquery 1.1.2
133
jquery 1.1.3a
2
jquery 1.1.3
2
jquery 1.1.3.1
37
jquery 1.1.4
12
jquery 1.2
6
jquery 1.2.1
143
jquery 1.2.2b2
8
jquery 1.2.2b
1
jquery 1.2.2e
1
jquery 1.2.2
68
jquery 1.2.3a
1
jquery 1.2.3b
3
jquery 1.2.3
545
jquery 1.2.4a
5
jquery 1.2.4b
1
jquery 1.2.4
13
jquery 1.2.5
3
jquery 1.2.6
1602
jquery 1.3
220
jquery 1.3.0
2
jquery 1.3.1
374
jquery 1.3.2
4857
jquery 1.4
526
jquery 1.4.0
28
jquery 1.4.1
684
jquery 1.4.2
6709
jquery 1.4.3pre
11
jquery 1.4.3rc2
1
jquery 1.4.3
611
jquery 1.4.4
2639
jquery 1.5
480
jquery 1.5.0
83
jquery 1.5.1
1274
jquery 1.5.1-1.8.11
1
jquery 1.5.1.min.rev-7
1
jquery 1.5.2
1163
jquery 1.5.
20
jquery 1.6pre
2
jquery 1.6
539
jquery 1.6.0
16
jquery 1.6.1
1443
jquery 1.6.2
1735
jquery 1.6.3
135
jquery 1.6.4
2511
jquery 1.6.x-1.8.x
5
jquery 1.6.x-1.8.x-1.2.x
1
jquery 1.7p1
13
jquery 1.7
1904
jquery 1.7.0
195
jquery 1.7.1
7629
jquery 1.7.2rc1
2
jquery 1.7.2
6418
jquery 1.7.3pre
1
jquery 1.7.x
1
jquery 1.8
431
jquery 1.8.0
603
jquery 1.8.1
1061
jquery 1.8.2
2143
jquery 1.8.3
7259
jquery 1.8.23
1
jquery 1.9
2
jquery 1.9.0
720
jquery 1.9.1
4336
jquery 1.10
2
jquery 1.10.0
104
jquery 1.10.1
502
jquery 1.10.2
13741
jquery 1.10.2-pre
1
jquery 1.11.0
227
jquery 1.11.0-beta2
2
jquery 1.11.0-rc1
1
jquery 1.11.1pre
1
jquery 1.12.2.1
2
jquery 1.12.2.3
158
jquery 1.18
2
jquery 1.20
48
jquery 2.0
4
jquery 2.0.0
78
jquery 2.0.1
5
jquery 2.0.2
36
jquery 2.0.3
295
jquery 2.1.0
44
jquery 3.0.4
24
jquery 3.0.5
17
jquery 16
1
jquery 17
4
jquery 170713a
2

jQuery UI

Loads of different versions

jquery-ui-autocomplete 1.8rc1
1
jquery-ui-autocomplete 1.8rc3
5
jquery-ui-autocomplete 1.8
27
jquery-ui-autocomplete 1.8.1
51
jquery-ui-autocomplete 1.8.2
226
jquery-ui-autocomplete 1.8.4
100
jquery-ui-autocomplete 1.8.5
329
jquery-ui-autocomplete 1.8.6
125
jquery-ui-autocomplete 1.8.7
101
jquery-ui-autocomplete 1.8.8
15
jquery-ui-autocomplete 1.8.9
122
jquery-ui-autocomplete 1.8.10
42
jquery-ui-autocomplete 1.8.11
157
jquery-ui-autocomplete 1.8.12
95
jquery-ui-autocomplete 1.8.13
158
jquery-ui-autocomplete 1.8.14
218
jquery-ui-autocomplete 1.8.15
47
jquery-ui-autocomplete 1.8.16
1542
jquery-ui-autocomplete 1.8.17
159
jquery-ui-autocomplete 1.8.18
449
jquery-ui-autocomplete 1.8.19
18
jquery-ui-autocomplete 1.8.20
88
jquery-ui-autocomplete 1.8.21
141
jquery-ui-autocomplete 1.8.22
75
jquery-ui-autocomplete 1.8.23
398
jquery-ui-autocomplete 1.8.24
376
jquery-ui-autocomplete 1.9m5
2
jquery-ui-autocomplete 1.9pre
1
jquery-ui-autocomplete 1.9.0
106
jquery-ui-autocomplete 1.9.1
200
jquery-ui-autocomplete 1.9.2
630
jquery-ui-autocomplete 1.10.0
137
jquery-ui-autocomplete 1.10.1
945
jquery-ui-autocomplete 1.10.2
218
jquery-ui-autocomplete 1.10.3
933
jquery-ui-autocomplete 1.10.4pre
1
jquery-ui-autocomplete 1.10.4
55
jquery-ui-dialog 1.5.3
1
jquery-ui-dialog 1.6rc6
3
jquery-ui-dialog 1.6
1
jquery-ui-dialog 1.7
3
jquery-ui-dialog 1.7.1
98
jquery-ui-dialog 1.7.2
205
jquery-ui-dialog 1.7.3
9
jquery-ui-dialog 1.8rc1
1
jquery-ui-dialog 1.8rc3
2
jquery-ui-dialog 1.8
27
jquery-ui-dialog 1.8.1
59
jquery-ui-dialog 1.8.2
236
jquery-ui-dialog 1.8.4
97
jquery-ui-dialog 1.8.5
326
jquery-ui-dialog 1.8.6
129
jquery-ui-dialog 1.8.7
114
jquery-ui-dialog 1.8.8
22
jquery-ui-dialog 1.8.9
120
jquery-ui-dialog 1.8.10
46
jquery-ui-dialog 1.8.11
189
jquery-ui-dialog 1.8.12
99
jquery-ui-dialog 1.8.13
167
jquery-ui-dialog 1.8.14
201
jquery-ui-dialog 1.8.15
43
jquery-ui-dialog 1.8.16
1510
jquery-ui-dialog 1.8.17
138
jquery-ui-dialog 1.8.18
455
jquery-ui-dialog 1.8.19
17
jquery-ui-dialog 1.8.20
88
jquery-ui-dialog 1.8.21
137
jquery-ui-dialog 1.8.22
74
jquery-ui-dialog 1.8.23
402
jquery-ui-dialog 1.8.24
380
jquery-ui-dialog 1.9m5
2
jquery-ui-dialog 1.9pre
1
jquery-ui-dialog 1.9.0
103
jquery-ui-dialog 1.9.1
200
jquery-ui-dialog 1.9.2
661
jquery-ui-dialog 1.10.0
134
jquery-ui-dialog 1.10.1
949
jquery-ui-dialog 1.10.2
210
jquery-ui-dialog 1.10.3
900
jquery-ui-dialog 1.10.4
55
jquery-ui-tooltip 1.8.8
6
jquery-ui-tooltip 1.8.16
12
jquery-ui-tooltip 1.8.18
4
jquery-ui-tooltip 1.9m5
2
jquery-ui-tooltip 1.9pre
1
jquery-ui-tooltip 1.9.0
106
jquery-ui-tooltip 1.9.1
196
jquery-ui-tooltip 1.9.2
559
jquery-ui-tooltip 1.10.0
134
jquery-ui-tooltip 1.10.1
944
jquery-ui-tooltip 1.10.2
212
jquery-ui-tooltip 1.10.3
899
jquery-ui-tooltip 1.10.4
53

jQuery-mobile

Betas and release candidates in use here

jquery-mobile 1.0b2
1
jquery-mobile 1.0rc1
1
jquery-mobile 1.0rc2
10
jquery-mobile 1.0
2
jquery-mobile 1.0.1
1
jquery-mobile 1.1.0
6
jquery-mobile 1.2.0
44
jquery-mobile 1.2.0-rc.1
1
jquery-mobile 1.3.0
18
jquery-mobile 1.3.1
15
jquery-mobile 1.3.2
38
jquery-mobile 1.4.0
6

YUI

The Yahoo User Interface Library is also quite widely used

YUI 0.12.2
5
YUI 1.8.1
1
YUI 1.09i
3
YUI 2.2.0
4
YUI 2.2.1
21
YUI 2.2.2
6
YUI 2.3.0
26
YUI 2.3.1
59
YUI 2.4.0
3
YUI 2.4.1
11
YUI 2.5.0
22
YUI 2.5.1
261
YUI 2.5.2
194
YUI 2.6.0
24
YUI 2.7.0
140
YUI 2.8.0r4
1298
YUI 2.8.1
58
YUI 2.8.2r1
43
YUI 2.8.2
1
YUI 2.9.0
1124
YUI 3.0.0
12
YUI 3.1.1
6
YUI 3.2.0
68
YUI 3.3.0
20
YUI 3.4.0
25
YUI 3.4.1
482
YUI 3.5.1
25
YUI 3.6.0
2
YUI 3.7.1
26
YUI 3.7.3
208
YUI 3.9.0
25
YUI 3.9.1
1
YUI 3.10.1
7
YUI 3.11.0
5
YUI 3.13.0
3
YUI 3.14.1
1

Prototype.js

Quite a number of versions in use

prototypejs 1.3.1
5
prototypejs 1.4.0
407
prototypejs 1.5
3
prototypejs 1.5.0
95
prototypejs 1.5.1
40
prototypejs 1.5.1.1
41
prototypejs 1.5.1.2
17
prototypejs 1.6
33
prototypejs 1.6.0
154
prototypejs 1.6.0.1
82
prototypejs 1.6.0.2
476
prototypejs 1.6.0.3
459
prototypejs 1.6.1
474
prototypejs 1.6.1.0
15
prototypejs 1.7
1268
prototypejs 1.7.0
8
prototypejs 1.7.0.0
40
prototypejs 1.7.1
63
prototypejs 1.7.1.0
261
prototypejs 2.05
1

Other

angularjs 1.0.1
26
angularjs 1.0.2
4
angularjs 1.0.4
1
angularjs 1.0.6
4
angularjs 1.0.7
6
angularjs 1.0.8
12
angularjs 1.1.4
3
angularjs 1.1.5
5
angularjs 1.2.0
1
angularjs 1.2.0-rc.3
11
angularjs 1.2.1
5
angularjs 1.2.2
3
angularjs 1.2.3
1
angularjs 1.2.4
21
angularjs 1.2.7
2
angularjs 1.2.9
2
backbone.js 0.3.3
1
backbone.js 0.5.1
1
backbone.js 0.5.3
11
backbone.js 0.9.0
1
backbone.js 0.9.1
2
backbone.js 0.9.2
40
backbone.js 0.9.9
111
backbone.js 0.9.10
8
backbone.js 1.0.0
51
backbone.js 1.1.0
8
dojo 0.0.0
16
dojo 0.4.1
1
dojo 0.4.3
3
dojo 1.0.0
2449
dojo 1.1.1
1
dojo 1.2.2
1
dojo 1.3.1
3
dojo 1.3.2
3
dojo 1.4.0
2
dojo 1.4.1
1
dojo 1.4.4
1
dojo 1.5.0
4
dojo 1.5.1
7
dojo 1.5.2
13
dojo 1.6.0
7
dojo 1.6.1
58
dojo 1.7.2
2
dojo 1.7.3
7
dojo 1.8.0
3
dojo 1.8.3
17
dojo 1.9.1
9
dojo 3.0.0
2
easyXDM 2.0.1
1
easyXDM 2.4.15.0
1
easyXDM 2.4.15.118
77
easyXDM 2.4.17.1
7
easyXDM 2.4.18.4
3
easyXDM 2.4.18.25
2
handlebars.js 0.9.0.pre.4
1
handlebars.js 1.0.0
12
handlebars.js 1.0.0-rc.3
15
handlebars.js 1.0.0-rc.4
2
handlebars.js 1.0.0.beta.6
1
handlebars.js 1.0.beta.1
1
handlebars.js 1.0.beta.2
6
handlebars.js 1.0.beta.5
2
handlebars.js 1.0.beta.6
5
handlebars.js 1.0.rc.1
8
mustache.js 0.2.3
2
mustache.js 0.3.0
6
mustache.js 0.3.1
17
mustache.js 0.4.0
20
mustache.js 0.5.0
2
mustache.js 0.5.1
1
mustache.js 0.7.0
11
mustache.js 0.7.1
105
mustache.js 0.7.2
22
sessvars 1.01
23