Many sites report that Apple has seeded iPhone OS 3.0 Beta 2 just two weeks after its announcement. For sure there are numbers of outstanding issues in the iPhone OS 3.0 Beta, and hopefully some of them are fixed in the second Beta. iPhone SDK 3.0 Beta 2 is also available.
As usual Apple Developer NDA is in effect, but the information is out there.
For those who are looking into installing iPhone OS 3.0 Beta (1, 2 and any of upcoming revisions) are advised to register as Apple iPhone Developer. It is relatively trivial to get the disk image, but the iPhone will not be activated unless it is registered in the development program. Downgrading to iPhone OS 2.2.1 is possible but not as simple.
Go scour the internet for the info on iPhone OS 3.0 Beta 2.