iPhone SDK beta 4 released with OpenGL ES support, code signing

Apple has pushed out a fourth beta of the iPhone SDK to registered developers. Thew latest build includes two primary new features:

OpenGL ES support: The iPhone emulator will now be able to render OpenGL ES in applications, matching the capabilities of the iPhone 2.0 software.
Code signing enforced: iPhone applications will now need to contain a valid certificate (obtained from the restricted, $99, iPhone Developer program) in order to be loaded on actual devices. If a developer does not have a certificate, apps will still run in the simulator but not physical devices.