Sony just released the PSP firmware 4.00 a week ago and already talks up the next firmware release 4.01.
The new upcoming Sony PSP firmware 4.01 includes minor updates.
Sony improves the display of search results under the new Google Search for some languages and the playback of video content has been improved for certain file types.
The new Sony PSP Firmware 4.01 is supposed to hit the Playstation Network in a few hours.
Via the Sony Playstation blog. Update: The Sony PSP Firmware 4.01 is now available. Via the Playstation site (Japanese).