Now what: iPhone G3? 4G? 3.0?
With calling last year's model the iPhone 3G, Apple brought a bit of trouble into the naming schemes. With iPods, we just called the generations 1G, 2G, 3G etc., the iPod classic is the iPod 6G, although it's rarely called that. The current nano is the iPod nano 4G. The current iPhone (the "iPhone 3G") is actually the iPhone 2G, the second generation iPhone. They can't well call the next iPhone the "4G", since the 3G's moniker stems from the 3G networks it's using, and there simply aren't 4G networks around just yet.
An iPhone Pro was mentioned in several rumours, which might mean that the 3G would stay on the market, at a lower price. It would be an interesting option, although it doesn't seem very "Apple". I personally hope they'll just call it the iPhone again. We'll call it 3rd generation or 3.0 or just "2009", but the standard iPhone model should just be called iPhone in my opinion, like the iPod was before the arrival of the "classic" (which basically meant that it was a dying breed, you don't call anything "classic" if it's not about to die).
But what about the other models? If there really is going to be a larger format tablet and an iPhone mini or nano, we'll certainly have to forget about the generation naming scheme again.