Maybe this explains, at least in part, the new iPhone 3.0 Beta 5released yesterday? Looks like Apple is super-eager to get developers testing and submitting 3.0 compatible applications.
We're really eager to see what developers are coming up with to leverage all those great 3.0 features as well. Really, really eager. Ahem.
Full text of Apple's email to developers:
All apps must be compatible with iPhone OS 3.0