it has to be 6. as the 4S is the fifth generation iPhone. it would make no sense calling it the iPhone 5.
I totally disagree. The majority of consumers have no idea that the next iPhone is the sixth generation. They don't keep track like some MR members would. "iPhone 5" would work just fine as a name.
I'm skeptical that we are getting a 4G iPhone next fall. I think instead we will see a redesign in the next generation (4" screen, thinner) and then we will get a 4G iPhone in 2013. While 4G and a redesign next fall would be ideal, I don't think it will happen.
As for any next generation iPhone talk, I'm burned out after discussing it leading up to the keynote a few weeks back. I don't have it in me to discuss it on here until the weeks leading up to the next iPhone. So probably next fall.