Dark_Alex has just released 2.71 Special Edition - Revision A custom firmware. Heres what the readme has to say:
This is a custom firmware that lets to have in a single flash the advantages of firmware 1.50 and
2.71 at the same time.
Homebrew can be run on both kernels, the 1.50 one and the 2.71 one, letting almost all current homebrew
to work on the 1.50 kernel, and 2.71 homebrew compatible with HEN C in the 2.71 kernel.
Note: the installer writes to FLASH0. I'm not responsable of any damage of what happens,
since this software is provided free and without warranty. TA-082 users cannot use this because a 1.50 bootstrap is needed to boot the system patched.
At the moment, there is only installer for 1.50, although it could be easily ported to whatever
firmware with kernel access such as 2.60 and 2.71, but at the moment i prefer not to doing it to avoid
TA-082 using it and bricking their psp's.
Note that this package DOES NOT contain any illegal material. The user has to provide the 1.50 and
2.71 updaters pbp's to legally generate the DXAR file used for the flashing.
Reminder: This flashes to your PSP. Use at your own risk.