Apple offered very little detail, but said that "iTunes 10.1.2 provides a number of important stability and performance improvements. iTunes 10.1.2 syncs music, movies, and more with iPhone 4 (CDMA model) and provides a number of important stability and performance improvements."
So if you've been twiddling your thumbs, waiting for Verizon to release their iPhone, this update will give you something to pass the time. Our esteemed readers have probably already picked out their new Verizon iPhone case. Until February 10th, don't be embarrassed to continue pretending your iPod Touch is the real thing.
source: iTunes via TUAW