Here are a few other interesting links shared with me by Chad Fennell, from the U of M:
Ethnio, a web-based tool to intercept users on your website, so you can recruit them for UX live research.
Regarding the Drupal tests, some of the resulting documentation - gives some sense of impact and adoption of the recommendations that resulted from the tests: Chad is also very involved in the Drupal project, working in the area of usability. Drupal is an interesting case, and appears to be fairly unique among open source projects for their community focus on usability.
The last round of testing:
The resources section contains links to participant videos, the issues cue matrix that resulted, etc.
Here is where most ongoing usability discussions happen (outside of IRC):
Drupal usability discussion
A good place to ask more question: #drupal-usability on freenode.