Hi Bruno, it would of course be great. Check out http://code.google.com/p/winetricks/source/browse/trunk/tests/winetricks-tes... for starters, we could just run that (or a subset of it) daily. It's fairly reliable, as I ran it manually every week for a while and weeded out a lot of flaky bits.
When I get a chance, I'll try integrating that into buildbot. - Dan
p.s. As Henri mentioned, it's been on people's minds for years. The graveyard is littered with previous attempts, e.g. http://web.archive.org/web/20070209153523/http://www.cxtest.org/ I think it's important to do the easy part first and not do anything fancy.