This plugin, called screensaver.prx, allows you to turn your PSP into a very low energie consumer mode if you don’t use it for some time.

Here is what it does:
-Turns your psp into “sleep” mode after a time you set.
-Puts it to very low CPU frequency (you can set it too)
-Shows the hour while in sleep mode.

http://forums.qj.net/showthread.php?t=130682