Apple have announced the release of the iPhone SDK beta 4 Build 5A258f.

This new build also includes support for OpenGL ES which will enable developers to actually see how the iPhone renders graphics for their software applications.

Another new feature include in the SDK is enforced code signing. Basically what this means is that from now on iPhone applications will need to contain a valid certificate (from the iPhone developer program).

If the developer doesn't include a certificate then the apps will still run in the simulator but not on physical devices.

This is the third build release since the iPhone SDK was release back in March.

iPhone SDK Beta 4 can be downloaded from the developer.apple.com website.