Also http://rstat.us, which I just found out about - not sure why it hasn't received more attention. It seems to be like a better identi.ca that can also automatically syndicate your Twitter posts. http://blog.steveklabnik.com/posts/2011-03-23-announcing-rst...

Edit: They're also planning to create a Twitter-compatible API, so a vendor like Tapbots could simply change the endpoint in their code and support rstat.us as well. https://github.com/hotsh/rstat.us/issues/562