Alright, I've done a quick port of the bootloader to the 3.XX kernel.
Prebuilt:
http://localhost.geek.nz/psplinux/ucboot340.tar.bz2
(Install in PSP/Game3XX. Get vmlinux.bin and pspboot.conf from the kernel package, put them in the same dir)
Source:
http://localhost.geek.nz/psplinux/ucboot340_src.tar.bz2
(make in /kernelmodule/, make in /, copy kernelboot.prx and eboot.pbp)
I've tested on my 3.40 OE psp phat. I'm interested to know if it works for others ( slim?

I (Noquarter) have tested it on my 3.71m33-3 slim and can confirm it does work on 3.71
