As of last Friday, Wikipedia started using Mono for indexing and searching the Wikipedia, it was tested first on one server and it is now being used on all three servers.
Wikipedia's search backend uses Mono and dotLucense, the same search backend that is used by Beagle Desktop Search. Previously, Wikipedia had been using GCJ and Lucene to do the searches but after some tuning, Mono became the new engine.
Mono 1.1.6 which was the originally tested configuration was slow, but version 1.1.7 introduced our simplified IO layer which improved IO performance significantly (2x-3x) and upcoming versions will an extra boost on IO, but most importantly the regular expression library (which MediaWiki uses) will also get a performance boost.
Mono: Debian and Ubuntu.
Mono is now on Debian/Unstable.
The details about this adoption are here.
Mark Shuttleworth announced today at his keynote in Guadec that Mono had been integrated into Ubuntu. He is looking forward to integrate IronPython into the distribution as well.
Usability in Gnome
Calum, I think I mentioned that Sun did usability studies, but I should probably stressed that more. I was refering mostly to the fact that we sometimes argue about usability, but do not have the data to back it up.
I will be eternally grateful to Sun's work on Gnome usability testing and of course its code contributions.