PSP firmware 5.05 released
But only on a Japanese UMD

The PSP has had another minor titivation to its firmware, courtesy of Sony, which has bumped the version number up to 5.05.
The twist in this very small tale is that the update has only been released on the UMD of Japanese game, Idolmaster SP. Whether or not Sony considers this to be enough of a necessity to give it a full release is currently unknown, and as there’s no changelog, we don’t even know what the update is for.
Presumably it’s there on the Idolmaster SP disk as it’s an update specific to that game, and isn’t changing anything the rest of us would need. It’s a tad disconcerting that if one new game needs fixing, others might, however.
For now though, there’s no cause for concern or a mad rush to get updating your PSP. If we hear of anything cool it does to upgrade your hardware, we’ll let you know.
C&VG