Apple has released the latest Beta SDK on 4th May 2010. The latest is now Iphone SDK 4.0 beta 3 that is on the Apple website ready for developers to download.

We haven’t taken a look yet as to what is included, but do recommend that if you plan on testing that you be prepared for the worst and anything you get will be better. What we have heard is that the camera now works on the iPhone with this beta installed, and it runs more stable than previous versions.

We do not know the official iPhone OS 4.0 release date just yet although some rumours are pointing to early June where it is also expected that the Apple iPhone 4G will be launched.
Back to the SDK, if you are a developer then you can grab it from over

(Via gadgetvenue.com)