It's currently only open by invitation but you can read about it here:
http://radar.oreilly.com/archives/2007/03/freebase_will_p_1.html
Might be an interesting model to consider or perhaps even the platform
for an open wine database?
-James
That said, it might be so darn easy to start an open wine database
with freebase or google base, that someone will just do it and start
using it. Like the microformats: we could spend a ton of time trying
to develop the perfect format, but then someone just comes in and
starts using one (Scrugy) and it works well enough. The people who use
these data and formats are going to be the ones who dictate how they
work. Anyway, end rant.
Jason