I'm not so sure the name will change. It's confusing to change names during iterations, and Apple typically doesn't do it; most of us concede, as well, it's only a hardware upgrade. If it does get a name I think it'll be "iPhone2" or "iPhone 3G"(the 3G variant making it appear Apple invented 3G or something, which is clever), but names like "iPhone Black" are confusing. Remember: this is the company changing to .Mac to .Me.
If the certain rumors stand that there will be a "cheaper," hardware-retarded cousin to "iPhone2," then maybe the naming will get snazzy -- differentiating between the original and the extension. I doubt this rumor though(I'll admit it may be because I don't like it and not because it doesn't make sense).