iPhone OS 2.1 beta 3 is now available and is to be used for testing only. View the Pre-Installation Advisory for iPhone OS 2.1 beta 3, Readme, and Release Notes before installing the new versions of the iPhone OS and SDK. As a reminder, pre-release software is Confidential Information and is subject to the terms outlined in your Registered iPhone Developer Terms and Conditions with Apple.
Again, there were 8 betas released for 2.0 between March and July. If Apple keeps this up, could we be looking at a September release for 2.1?