Freeplay released his exploit for the game Mercury a few hours ago. The reason is that the vulnerability has been patched in firmware 6.20, making any further work on this exploit useless. Sony also immediately updated the game on the PSN store so that it now requires firmware 6.20.
Matieuhlh, member of the team prometheus (the team who created the Pandora Batteries), and a respected hacker on the PSP scene, revealed that Freeplay actually stole the code from a private SVN. To prove this, Mathieulh released the original sources of the exploit, as well as the sources for a kernel exploit that has been patched in firmware 6.00.
Further development of these exploits will most likely lead to custom firmwares and/or HEN for PSPs up to the firmware 6.00. This is of course interesting only for owners of Ta88v3 and of PSP3000. Owners of PSPGo can still pray for a future XMB exploit, and owners of older models of PSPs can use pandora batteries, independently of their firmware. As usual, if you like homebrews, don’t upgrade. And avoid buying a PSPGo
People interested in working on these vulnerabilities (user and kernel) can download them here