They've been out for many years... they were actually out long-before the iPhone was released. They used to run Windows Mobile for the mostpart, with the odd exception, and some were exactly the same size, shape and design.
They could still be running Windows Mobile at the core, there is many skins for it which turn WinMo into an Iphone lookalike OS, but I know there were at least some that were running their own OS. Why anyone would want to bother imitating the iPhone OS is beyond me, sure Android with Sense or WebOS would be a better choice now? Bah, probably too complicated to copy lol.