from Hellcat:

What is this? And why?
- Flashes a fresh M33 CFW (3.71, 4.01, 5.00)
for recovering semi-bricks or to up-/downgrade CFW
- does not use Pandora, runns from the recovery menu or the XMB
- does not use (as in launch) the original Sony Updater (only extracts
all required files from the original .PBP)
- runns fine on CFWs lower than 3.52-M33-3 - handy for upgrading older
FWs w/o the "need to go 3.52, then 3.52-3, then higher" odyssey :-)
- runns fine from TimeMachine (3.40-OE on Fat and 3.60-M33 on Slim)
- can backup the FW flash and restore selected parts (XMB theme,
settings, PSN activation, complete firmware)

Changelog:
* Added native support for installing a fresh 5.00-M33
* Added option to cache the special modules from all updater .PBP currently on your memstick.
The modules are saved seperately and - if present - used directly instead of extracting them from the required updater (again) when performing a restore of a backup.
This way you can save space on the memstick by deleting the updater .PBPs if you don't need them otherwise.