"A new leaked iPhone prototype design hints that the iPhone is on its way to T-Mobile
. Also, Apple may release a refreshed iPhone 4
(something like the 3GS was to the 3G) with a similar exterior but and enhanced processor."
The refreshed iPhone, known as the iPhone 4S with the enhanced A5 processor won't see a public release, it's only for developers to test out their applications. What applications, I don't think we know yet, but it may be for iPhone 5 testing, because that A5 processor is what will probably be in the iPhone 5.