It looks like Steve Jobs jumped the gun in sticking with the iPhone name, which is owned by Cisco. The two companies were in negotiation as Jobs took the stage on Tuesday to introduce his new mobile device, but didn't find a common ground…at least not soon enough. Cisco's final efforts to make a deal were apparently rebuffed or ignored by Jobs. The two companies had an idea to share the brand, to make clear their differentiation (which would  be hard to do), to have their products interoperate, and to announce the deal by Macworld.

David Berlind covers much of the iPhone trademark history here. Following is Cisco's release:

Cisco today announced that it has filed a lawsuit in the United States District Court for the Northern District of California against Apple, Inc., seeking to prevent Apple from infringing upon and deliberately copying and using Cisco’s registered iPhone trademark.