Appleiphoneapps.com writes:
"As if developers don't have enough to worry about when submitting their applications for approval at the App Store, Apple has decided to throw in another curveball.
Apple has sent out an email to all developers stating that beginning today, all application submissions to Apple's App Store will be reviewed on the latest beta of iPhone OS 3.0. This of course means that they will currently be reviewing App Store submissions on iPhone OS 3.0 beta 5. If your application is not compatible, it will simply not be approved."
Always good to think ahead.