Bottom area of the S3 gets hot for the same reason the top part near the camera gets hot on an S2 - the cellular radio systems are located there.

Not so sure which genius thought it was a good idea to put the heat generating parts closer to the users hands though.

Anyways, planning on buying the Mercury Color Screen for the S3 and give myself the Black S3 Samsung denied me. Yum.

It's out. There's even two versions out already, flat and curved - both fully cover the screen IINM.

Not sure if the local guys have it though, I tend to import my stuff myself.