I just ordered the iPad Camera Connection Kit, not because I want to connect my camera to the iPad - though that might be useful now and again - but because people are reporting that you can connect a USB keyboard to the iPad that way, and you can connect USB microphones as well.
That could be very useful since I've started to use the iPad to record meetings while also taking notes; unfortunately the tap-tap-tap on the screen keyboard gets recorded too, so it would be nice to use an external mic! The application I've been using is called SoundPaper. It's very basic, but lets you record wile also making notes.
Unfortunately, delivery quoted from the Apple Store is two to three weeks on the Connection Kit.