I'm doing Android dev on a couple of phones (Hero and NexusOne) and have played with the SDK 3.0 preview tablet virtual device... find it _very_ slow and unresponsive compared to the phone emulators. Hopefully this will be fixed soon.
I had hoped we'd see a lot more Android tablets in 2010 but, now that 3.0 Honeycomb is out, it should get interesting.
I'm holding out at least until mid-year to get a tablet. I've seen talk of quad-core devices and one of these would do very nicely. Until then, my tablet dev will be on the SDK's emulator.