So, it's been raining virtually non-stop here
 

because of the effects of Alex. Well, this morning I went to load up some wheels and tires into the back of the car, and I discovered a pool of water down in the hatch area. I didn't see any obvious place where the water got in. I'm pretty sure the hatch was closed... Any ideas?

check and make sure the weather stripping is pushed down on the metal around the bottom, mine pulled up a little bit in the middle once and i had the same thing.

Yeah, that was my first suspect - the rubber right in the middle above the decals.