If you did not spot it already Apple has released a beta for iOS SDK 4.1 today, download it from the iPhone Dev Center. Like all Apple pre-release software this is covered by NDA so not much more I can say - but since I did not find time to look at it yet I can at least speculate….
Apple has previously said that it expected to ship iOS 4 for the iPad in the fall. From the timing I guess that could still be 4.1 if it stays in beta for the next three months but that seems a long time. Otherwise this may be a quick and less interesting release to address some of the reported issues with iPhone 4 which would mean we may still see a 4.2 over the summer.