I'm pretty sure that the 3000 series is still "locked down." Which was what their release and all the upgrades to firmware were mostly about: to stop people from installing homebrew firmware that allowed them to pirate games on the PSP. Originally, the way the firmware for the PSP was set up, the homebrew community was able to create games for the PSP. However, this was exploited to install the firmware in question.
You may have already stated this in your post, but I might have missed it.
The original PSP OFW allowed you to play un-signed games... essentially allowing Pirating to be easy as s***, so Sony changed it
The first two PSP models were ORIGINALLY hacked using "Pandora" batteries (I actually own one), but for a long time even 3000's could be hacked momentarily with temporary firmwares you had to reinstall if the PSP ran out of Battery power.
However, in the quite recent months, this has quickly changed.
What has happened is that the Homebrew devs have found out how to "Sign" their games/CFW installers... this allows them to let people without hacked PSP's, Pirate "Signed" Pirated Eboots (the name for sony's PSP Games)
This also allows people to easily use exploits, and Sony knows this. You know your platform is screwed when the firmware update is hacked ten seconds after it goes online, and hacking is easy to do in about 5 minutes.
Nowadays there are two major CFW's; PRO, and ME. Both are available on ALL PSP's, and PRO works permanently on every model available, including GO.
So, what does this basically mean?
-ANYONE can Pirate on even non-hacked PSP's
-EVERYONE can hack their PSP(s)
-NOTHING Sony can do can stop pirating on PSP's now.