"Yes you do" - kinda.... mostly....usually.... yes
You need access to an already homebrew enabled PSP, then you can flash the battery with one of the various pandora makers.
The kinda mostly stuff is there are some pandora flashers that will enable you to use the battery as both a pandora and a normal battery at the same time, without re-flashing to the normal state.
Also you could hard wire the battery to be a pandora battery, and you wouldn't need a new battery. All methods however; you will require the Pandora/Magic Memory Stick files once again there are some modified ones that will install the latest custom firmware or whatever instead etc, just a matter of tracking them down (not hard, all available from the major PSP news sites) and choosing which one to use.
[end of off topic]
Anyway hope you enjoy your iphone and don't feel stupid when the new model comes out soon
/ 
