A Bluetooth dongle for the Sony PSP has appeared in Asia.

Chinese Ever-e has the Sony PSP Bluetooth dongle listed. Supernova Intelligent High-tech, also a Chinese electronics company offers the same Bluetooth Sony PSP accessory to OEM customers.

This Bluetooth dongle is shaped to fit on the side without sticking out too much. Measurements are 126mm x 30mm x 20mm. It supports Bluetooth 1.2, up to 10 meters.
I could not find yet in a store. Of course you could use any Bluetooth Dongle to connect it to the Sony PSP, but it would not fit as nicely as this one.
To have the Sony PSP support Bluetooth was one of the feature requests from I4U readers earlier this year.