Guys, as a developer, I just took a look at the API diff and "what's new in iPhone OS 4" docs, and I saw some gems Steve didn't talk about !
For instance, Grand Central Dispatch is now integrated to iPhone OS 4 (!!!!!!!), and UIKit is now "thread safe"... those two tips make me think that the next iPhone will probably be MULTICORE!
Another interesting point in the doc, is the description of the new framework, accelerate :
"The Accelerate framework (Accelerate.framework) contains interfaces for performing math, big-number, and DSP calculations, among others. The advantage of using this framework over writing your own versions of these libraries is that it is optimized for the different hardware configurations present in iPhone OSbased devices. Therefore, you can write your code once and be assured that it runs efficiently on all devices."
I don't know you, but the word "DSP" is flashing red before my eyes!
Now that Apple master their own CPU production, I bet that the next A4 evolution that will ship with the new iPhone will be multicore and will get a DSP or the equivalent to the MMX addon the x86 have!