Success! Breakthrough with successful payload delivery, code execution and exploitation has happened. Both a Palm Pre and an N900 have been used, by completely separate developers, to "jailbreak" the Playstation 3.
Using a modified kernel driver, KaKaRoTo has been able to successfully emulate multiple USB devices to deliver his payload for the psgroove vulnerability, giving you the ability to run unsigned code and opens doors for developers, hackers and homebrew'ers. PSFreedom.
He has said source and all will be released shortly, but has provided the kernel driver, compiled against the stock OMAP1 kernel for the N900. It's literally plug and play.
Meanwhile, Hector Martin has been working with his OMAP3 beagleboard, and has received word from a fellow tester that he was able to tinker with gadget and sysfs enough on his Palm Pre, to deliver the code to a PS3 sporting 3.41 firmware.
I prefer the userspace approach, however once KaKaRoTo releases his source, I'll be compiling it for my kernel and giving it a shot!
Ain't this device just the best?