The LG Optimus Pad (horrible name aside) is also looking pretty good. I think the 8.9" screen might be the perfect size (not too big, not too small), and the resolution is the highest of all of them. The 3D part doesn't excite me, and I hope that doesn't drive the cost up too far. Edit: Wrong about the LG's resolution being the highest, I think, but I still like the size.
Whichever tablet of the three--Samsung, LG, or Motorola--is available first in a wifi-only, 16GB version for $599 or less is the one I'm going to get. If none of them fit those specs, then I'll get the cheapest one.