Apple has implemented a system for differentiating applications in the AppStore and for some time you could notice that some applications have a small plus on their right, well for those who didn't know that plus is put there to warn users that the respective applications they are compatible with both the iPhone/iPod Touch and the iPad tablet.
For the applications compatible with iOS 4.0 and the new APIs, there is still no differentiating element, but I am sure that Apple will soon introduce something for this in the idea of alerting users which applications are 100% compatible with iOS 4.0 and which are not.
