A while ago there was a video of an alleged iPhone 5 floating around the net. It looked identical to the Verizon iPhone, including the antenna gaps in the same places, just with a SIM slot. Might be safe to assume now that this will be the next iPhone.
Certainly good news for iPhone 4 owners, because even with new chippery inside (dual-core CPU?) and CDMA/GSM capabilities the phone will be (and look) very much the same and such the iPhone 4 won't look "old". Apple did the same with the iPhone 3G and 3GS. Helps a lot not to devaluate quite new but essentially obsolete hardware.