Update: It's possible that the 480MHz CPU speed mentioned in the report referred to a USB speed, 480 Mbits/sec maybe? We'll keep you posted when things become clearer.
Whilst the official spec report from Sony rated the PSP Go processor at 333MHz, a recent test report filed with the FCC indicates that the PSP Go processor runs at 480MHz. The original PSP was clocked at just 222MHz and the 333MHz mode was only made available after several firmware updates. There is no way for PSP 1000-3000 owners to choose this CPU clock frequency, this is all down to how developers write the games.
It's most likely that the PSP Go will be locked at 333MHz on the release day, with the 480MHz mode being made available to developers later on in the product life cycle One of the disadvantages of running a higher clock speed is lower battery life and all of those extra clock cycles eat more power from the PSP Go's tiny battery. As the PSP Go has a fixed internal battery there's no possibility of carrying a spare, so perhaps it's best that Sony release these handheld devices locked at the lower clock speed. It certainly makes battery life figures look better on the hardware spec sheet.
PSP Go CPU Speed, FCC Report, PSP Go 480MHz