Perhaps you should read around the subject before posting? Last time I checked there was no need to use a stolen SDK to write a flippin' web page. PSPIRC is just that, a web page that is designed to fit the PSP screen.
The only true hacking has been the dissection of updates and save files in order to better understand the PSPs file structures. Since the executables are AES(?) encrypted, there's not too much chance of learning much more that way.
The most likely way into the system now without Sony's help is to find a buffer overflow and exploit it. The media and picture views seem to be the most likely suspects, as several bugs have been found already.