I just posted a LibraryThing widget on my WP blog and the javascript is working like a charm. It was very, very simple to do so I'm posting instructions here (as I couldn't find any):
1. Open up the WordPress control panel/dashboard (sorry, but only I can open mine)
2. Click on the “Presentation” tab
3. Open up the “Widgets” tab that should now appear.
4. Scroll down the page and click on that dropdown box under “textbox widgets” and select the next number that appears (for example, “1″ is set as the default so select “2″). That will create a new box under “Available Widgets.”
5. Click and drag that new box to the appropriate sidebar.
6. Double click on that box and a new window will show up.
7. Enter the widget’s heading in the top box on the new window.
8. Enter the code into the bottom box on the same window.
9. Click on “Save changes” which appears on the right side of the screen.
10. You’re done!
After you've created the new text widget, cut and paste the code from LibraryThing into the widget box (after you've moved it to one of your sidebars) and that's it. Hope this saves others some time - it took me several hours to figure it out.