The Miselu C.24 is the iPad case which features a fold out two octave keyboard. its got Bluetooth connectivity and will also get some extra drop-in controller modules soon. Originally launched on Kickstarter, it has taken a while to get to production, but it looks like we'll be seeing them coming in a month or so.
Interestingly, Jeoff Horton also sits on the MIDI Bluetooth group, and gives us some information on how that is coming alog.