Claiming they have the best CPU after a couple of minutes testing the device as an end user seems way over the top. It's also not likely that the same CPU could simply be put into a phone.
On the contrary, it is extremely likely that the A4 will be in the next iPhone. The CPU architecture is the same (ARM) and the peripherals are the same (video, etc.). It is an Apple ARM-SoC[1] rather than a Samsung/PortalPlayer/TI/whoever ARM-SoC[2]. The functionality is a perfect match, the physical size is likely to be a close match, the speed is much better, and the power efficiency appears to be similar or better (the iPad undoubtedly has a much larger battery).
Look at the heritage: PA-Semi created a remarkably fast, remarkably low power PowerPC architecture SoC. They are very, very good. Apple bought them so that they could use that power, speed, and efficiency knowledge to create the A4. Reports are that they used the fast ARM Cortex A9 core and did their magic on the peripheral parts of the SoC. That is exactly what all the other ARM licensees are doing, except the others (arguably) don't have the same talent level as the PA-Semi engineers.
