Since the message of WGA running under wine, wine has seems very promising to me. I tried running WGA on my own pc, it didn't succeed, badly. About a month after the message of WGA under wine, I have, after updating wine to 0.9.40, tried running windows update under wine.
Most of you will only know windows update as the application which runs on your PC 24/7 and does some checks every now and then. But, there is also a webbased version, and it appears it can run on wine without any hassle after installing ies4linux.
The only thing i had to modify was the security level. Because i am too lazy to sort it out, i just set it to minimal (tools->internet options->security->security level for this zone->low)
Then, browse to
http://update.microsoft.com/ , it didn't even ask anything, it just went on to installing two updates.
All this was done on Gentoo Linux (architecture mostly x86, wine and some other things ~x86).
http://arch.kimag.es/share/96526402.jpg
Wine sure is promising...
ps: let's see how fast this message reaches digg and slashdot