Philocrites asks "Is Textpattern the CMS solution for Coffee Hour?" in the Miscellany section of his blog.
Uh, no, I don't think so.
Textpattern, in my experience, was by its eccentricities more trouble to learn than it was worth. Each time -- and there were several, as it promised to be the solution to several projects -- I found the learning curve high, and the community support and results dim.
Everything I hoped to do with Textpattern I accomplished with WordPress. Chutney was the first UU blogger I know of who adopted WordPress, but others (myself included) have been converting over at a reliable rate. The free wordpress.com beats the pants off of Blogger, and makes migration easy by the way.
Drupal would be a better option for heavy-duty portal or community development portals. Perhaps that would be a better option for Coffee Hour. But I'd stay away from Textpattern which suffers from being good for some, but not good enough.