I'm using a Wacom Bamboo tablet with LR2 on a Vista system. LR recognizes the pen, but not pen pressure. Nor does it distinguish between the "writing" end of the pen and its "eraser" end. So, in short, the functionality of the tablet is severely limited in LR2.0, at least in a Vista environment.
The pen, pen pressure, and erasing all work perfectly in photoshop.
Adam