[catshirt]

i threw some example code [1] on gist to supplement my comment. i modified it a bit and didn't test it- but it used to work- so probably still good for reference. it's also not very pretty. questions, comments, concerns welcome.

essentially, it gives you two-way communication to your server on any arbitrary domain- that's pretty powerful!

[1] https://gist.github.com/1020251

[buddydvd]

Instead of polling, you can define event handlers for <script>'s onload and onreadystatechange event to detect when jQuery gets loaded. See Ben Alman's jQuery bookmarklet generator for an example: http://benalman.com/code/test/jquery-run-code-bookmarklet/