I am one guy who absolutely loves his IPad for certain keyboard apps! And check out the alesis wireless midi controller keytar!
http://alesis.com/vortex-wirelessUsing the camera kit connecter in my IPad I can wirelessly connect to some wonderful apps such as Magellan, an awesome synth app. There are many great keyboard apps to be found if you search for them.
I tried the novation UD refers to and it is very good and can be used for many other apps besides the Launchkey/Launchpad.
The Alesis Vortex just seemed like a no brainer for me when I came across it. And I love it and I've barely scratched the surface using it. (I've been pretty busy with the S950 I just got a few weeks ago)
But do yourselves a favor and if you haven't already, check out the Wireless Alesis Vortex. Aftertouch, Accerometer can be Set to any parameter, lots and lots of goodies, all for $200.
What? $200? Yup, it's a LOT of bang for the buck!
Jim