Of Whales and Satellites

It would be really cool (and useful) to track whales via satellite imagery. Of course, the whales have to cooperate by being at or near the surface.  Assuming they are, can we spot them and tell that they are whales?  The Ikonos satellite service reports its WorldView2 satellite can spot whales. WorldView2 has a maximum resolution of 50cm, so a whale is going to appear of decent size: a whale showing 20m of back at the surface will be 40 pixels long and maybe 6 pixels wide (wider if the flukes are showing.)  There is a lag in how often one satellite in low Earth orbit (LEO) can look at a given patch of ocean, though, so it can't keep continuous track of a pod.
Planet Labs can keep continuous watch on an areas when it's finished deploying its nanosatellites (5kg each (really) and offering 3-5 meter resolution),  A whale may be only a pixel wide and a few pixels long, though, I had a chance to ask co-founder and CTO Chris Boshuizen about it at the Conference on Small Satellites. He's looked at this because people have sent in Planet Labs images and asked if some objects visible are whales.  Chris doesn't see whale-tracking from his satellites as practical: a whale is, at best, a tiny smudge indistinguishable from a boat. Planet Labs started out not intending to image watery areas at all but now goes out 40 km from all coastlines.  We also discussed whether whales, with their blubber insulation, have enough of a heat signature to be spotted in the infrared band (he doubts it).  He can spot pollution plumes in the water and sediment flows, though, so Planet Labs, which has a strong ecological mission, can contribute to the study of inshore habitats.  Thanks to Chris for taking the time to answer my questions!