Actually fusetalk fully supports mysql and is more powerful than both of the options listed. We also have an SDK with full access to the major API components, we have a mailing list addon that fully integrates with mailing lists, a support addon to do electronic support through the forums, and a NNTP solution coming soon that integrates with NNTP servers as well, something neither of the competitors you listed do 🙂.
We also support Oracle, MSSQL, Access. PostgreSQL is in the works along with Informix and Sybase for the future.