The description in Software Update may only say that it brings a "number of important stability and performance improvements," but Apple's just-released iTunes 10.1.2 update also adds another fairly important feature: support for the Verizon iPhone 4. That detail is tucked away in the "before you install" document included when you download iTunes from Apple's website (rather than Software Update), and actually only refers to the "iPhone 4 (CDMA model)," which you can read into what you will.
