Sony
Computer Entertainment Japan has announced the version 2.70 system
software update for Japanese PSP (Model PSP-1000). This update is
slated for 14:00, April 25, GMT+9:00 (1:00AM, April 25, EDT). Here are
the details of this update:

[Network]
- [Internet Browser] now supports Macromedia Flash contents playback.
*You need to enable the Flash contents playback in the [System Settings].
*The version of the flash player is Macromedia Flash Player 6 (a part of the functions is not supported). - The settings of the [Internet Browser] is added into [Settings] -> [Connection Settings]
- The audio contents from channels in the [RSS Channel] section now can be saved into your memory stick.
- [Auto] option added to [Rate Change] in [Location Free Player].
*More about the Location Free base station can be found [here].

[Music]
- Added file extension to playable AAC format.

[Settings]
- Added [Enable Flash Player] in [System Settings].
*To change this option, you need to connect to the internet. - "Simplified Chinese" and "Traditional Chinese" added to [System Settings] -> [System Language].
- Added [RSS Channel Settings].
- Added [UMD Video L & R Button] into [Video Settings].
[Others]
- Fixed some issues when using a memory stick with more than 2GB free space.
*This problem has not happened among the memory sticks sold in Japan until April 24.
So, there you got it. And please note that the old warning is still there:
"CAUTION: This update is only for customers who obtained PSP®
(PlayStation®Portable) for Japan (PSP-1000 series). Upon completion of
preparing, we will announce update information for the other countries/areas
customers via SCE Group Web Site or other channels . For these customers who
obtained PSP® in the other countries/areas, please DO NOT update PSP® through
this web site. There are no guarantee of proper operation of the other
PSP®."
You won't void your warranty, but it's not cool to do so in Sony's opinion. ;-)
Thanks for the email heads-up, Kynadr!
Source: PSPUpdates