Version 2.16 (April 04, 2009):

* Time Rewind feature: map 'Special: Rewind' to any PSP button in the Controls menu to enable. See documentation for more information
* Save state format has changed: RACE! PSP will still read the older save state format, but loading will be slightly slower
* Not a new feature, but the documentation now includes a section on how to have RACE! PSP load a BIOS ROM file (instead of using the customized hardcoded version)