Homebrew may be a step closer on the third generation PSP Models (PSP-3000), thanks to a new exploit discovered last week in the game GripShift. The exploit is confirmed to work on the PSP-1000, PSP-2000 and PSP-3000 and on all firmware versions from 1.52 to 5.02. The exploit will allow you to run homebrew games that do not require kernel access – as a result, a downgrader is not yet possible but be sure to keep a look out for new developments.
A SDK has also been released for the exploit so you can run your own code using the exploit. You can download the Hello World demo and SDK below.