According to BusinessWeek

they have reported that the Apple iPhone SDK will be late, there are only a few days left now to the end on the month to announce the iPhone SDK, a reliable source of BusinessWeek said that Apple will be delaying officially sanctioned 3rd party apps.

This means that it will be late by around about one to three weeks, so it seems Apple commitment to give us the iPhone Software Developers Kit is hanging around. We will let you know more soon as we find out from our sources.