Sony has released a new update in Japan that fixes previous security holes that were taken advantage of by crackers last week.
Version 2.01 is currently intended only for Japanese PSPs, however it is clear that it is Sony's attempt to stop crackers using the PSP illegally.
Sony's PSP site encourages users to download the latest patch, but only if they have a PSP with the system model number PSP-1001. Users who don't have a the model number PSP-1001 are advised against download and installing the patch as the company states there is no guarantee of proper operation with other models of the PSP system.
Oddly enough there appears to be no reference to v2.0 anywhere on the site, even on the system update history page.
Meanwhile some PSP fan sites are warning PSP users that a fake patch has been circulating the Net, and the faux update does nothing but render the handheld useless whilst voiding your warranty at the same time.