This isn't an exploit in the firmware. It requires a modchip with a custom BIOS to run. However, it IS an impressive step forward for PSP homebrew development.
In other news, firmwares 2.5 and 2.6 now have kernal access via the GTA exploit, meaning 2.5 and 2.6 users now have full homebrew capability. Check it out at http://pspupdates.qj.net