I just finished upgrading the Lanlogic Community Server to version 2.0 and boy am I impressed!
First off, the UI design is leaps and bounds ahead of 1.1. Telligent Systems, the maker of CS partnered with ComponentArt, to add some really nice UI controls to this platform.
So far the only error I've come across had to do with templates we were using on the site that were calling objects no longer in use in this version.
For those of you who aren't familiar with CS, this is a community site builder that supports blogs, discussion forums, photos, and file sharing. All searchable, all subscribable using RSS.
http://www.communityserver.org