There has been a section of the PlayStation Store specifically for the PSP for a while now. To get content purchased there to the PSP you had to buy it via the PS3 or a PC though, less than ideal.

According to TrustedReviews, a firmware update for the PSP will give direct access to the PlayStation Store via the PSP. There is no word from Sony on how this will work, but you could reasonably expect a new storefront similar to the PS3 to be added for direct Wi-Fi access of the store.

The feature is reportedly going to be available for all versions of the PSP, not just the newer slim PSP and the coming PSP-3000.

Via TrustedReviews