Would the A4 really be that big of an upgrade for the iPhone?
Considering the iPad has a battery thats ~3X larger than the iphone, the power use of the A4 at 1ghz is probably too high for the iPhone. And it has the same amount of ram as the current iphone. Apple would probably clock the chip down a bit if they used it in the iPhone.
Doesn't the iphone already have a 833mhz chip clocked down to 600mhz?
Since the last iphone update, the CPU has been about 31% boost in speed.
This would put us at: 786mhz on the new iPhone, which would probably be a good underclocked speed for the new iPhone.
I think it would be cool if they could make some kind of "turbo boost" like on the intel chips, work on the ARM chips. Leave the CPU way underclocked 90% of the time, and crank it up when were booting apps, or processing something. If the demand for 100% use remains longer than a few seconds, return to a lower power state. Otherwise we would loose too much battery life. Only short boosts for a few seconds would be reasonable.