There is also One Social Web http://onesocialweb.org/ which uses xmpp to federate the network. It has a server, web client and android client. It's open source and is being written by a vodaphone research team.
I've only just installed a status.net instance, how hard do you think it would be to bridge the two services? How hard would it be to create a plugin for status.net that talks xmpp and speaks the one social web protocol. Another approach may be to write a separate ostatus implementation that uses the java library from one social web and use that as a bridge.
