According to the official specifications of the PSP Go, the only difference in the hardware specs were the screen and the lack of UMD drive. However, according to the official listing of the PSP Go in the FCC, the PSPgo sports a processor that is almost 40% faster than the original PSP processor.
The original PSP models, which included the PSP-1000 through 3000, sported a 333Mhz processor. The processor was intentionally limited to 222Mhz due to heat and battery life concerns. However, a later firmware update (thanks to pleas from the developer of God of War: Chains of Olympus) unlocked the full speed of the CPU. Similar to this, the PSP Go will most likely be limited to the standard 333Mhz clockspeed and will probably be unlocked by certain limit-pushing applications, or even games.
The speed of the internet browsing on the new PSP may also be a new selling point, similar to what Apple showed off with the iPhone 3G S, and would explain Sony’s decision to use a faster processor. The PSPgo will hit store shelves this October for a retail price of $249.
Update: Special thanks to Kyle for the FCC Specs image.