I guess people who run Custom Firmware (CFW) are out of luck for now, but maybe not for long. It really has been a while since the last available CFW update. Dark Alex dot org site is currently unavailable for this month. Hopefully by the next one, his site will be up and running and with more PSP hackable content.
For now I am just sitting here waiting what happens... a lot can happen in just a couple of weeks when Gran Turismo comes out on October 1st (same day PSP Go launches).