XML RPC interface
Powerblogs now supports posting with an XML RPC interface. Specifically, users can use programs which support the MetaWeblog API with the URL http://blogname.powerblogs.com/admin/xmlrpc.pl — this might be especially handy for users who want to post from PDAs.
It also supports the blogger API, but the blogger API is pretty terrible — it doesn't even support titles. At some point, I'll probably implement as much compatibility with the MovableType API as possible, and likely also implement a Powerblogs-specific XML RPC API (I am toying with the notion of writing a java post composition program to go with Powerblogs to make disconnected post composition easier, but this is a really long-term goal, not anything which is going to happen soon).