Socialtext just released their wiki code under the OSI-compliant Mozilla Public 1.1 license. You can downloaded it here. The package is called Socialtext Open, and according to the press release, it is "the first open source wiki with a commercial venture as its primary contributor. Over 2,000 businesses run Socialtext Wiki products today as a hosted service or appliance." I'm on the board of Socialtext and we've been talking about doing this for a long time. Socialtext has always been an open source contributor, but this is a fairly important step forward and a shift in the business model. I think this puts Socialtext solidly on the right side of the open source movement.
Congratulations Ross et all.