03spaces is apparently integrated with OpenOffice and MS office, and allows people to collaborate on documents. It is mainly server based, but works over Webdav. It has document versioning and checkout.

http://www.o3spaces.com/

Not sure when I'll get the chance to play with it, but it looks interesting.

I hear what you're saying about Microsoft Enterprise Agreements. As it happens, for this project none of the entities is big enough to have that kind of agreement, and that's precisely why Collanos is a good fit for us. I'm also finding that it doesn't scale very well — the more people we add, the more problems we get — so I'd say there's definitely limited usefulness for larger groups. If I had to puts some limits on it, I'd say maybe groups of ten people or less, geographically dispersed, and not sharing any large files such as video content.

Versioning: one of the things I looked at while I was evaluating various groupware solutions was Alfresco (www.alfresco.com). While it works in a totally different way to Groove, Collanos etc, it certainly has the versioning thing nailed. SugarCRM addresses this to some extent as well.