I took a look at the commit log for Mesa, and I found this:
r600: bump glsl version
http://cgit.freedesktop.org/mesa/mes...3db12b1f1d52f9

From what I understand, Wine prefers OpenGL 2.1 so things should start working better with that.

I'm not at home, so I haven't been able to test it yet. Anybody tried it out yet?