We just got a new Samsung Galaxy, which runs Android 2.2, and one of the first things we tried on it was Skritter. It's fantastic! For writing and definition prompts, I think it's almost equal to the PC plus the Wacom. (The reading prompts are still kind of dodgy and don't seem to submit when I hit the return key, although they do kind of work.)
One thing which is a little strange is that it doesn't allow you to resize the page; there's a wide border of unused space around the edge, so it would be nice to be able to zoom in and use the whole screen.
James