
Our pals at PSP Vault have posted the details of a review of a Bluetooth Adapter by a Japanese site, heres the info in English.
A few highlights from the review:
-The adapter fits underneath the PSP quite well, and has two protrusions that slip right into the speaker holes on the bottom of your PSP for added stability.
-The package includes a USB cable (for recharging) and a 2cm stereo extension cable.
-The adapter is only one part of the package -- the company plans on including stereo Bluetooth earphones in one of two styles: neck band or ear-hanger.
-Audio quality is on par with that of the original PSP earphones
-There are no controls on the headphones (or a connector for the PSP remote), but they do have volume adjustment
-Reception is good; he said there were no problems when he inserted the transmitter into a nylon bag, and there were no problem when he walked into the next room (but left the door open)
Could Bluetooth be an option for the PSP Homebrew Scene in the future

Screenshots via the comments.