I created an OpenGL ES sample application that displays a textured cube, and lets you rotate it using touch gestures, as part of the class I teach on iPhone development. I warn you, though, I didn't quite get the faces right in that example, so it's up to you to correct my mistakes. The notes from that course, including the lecture on OpenGL ES, are available in VoodooPad format here.
For a more complex example, you can download the source code to my iPhone / iPad application Molecules.
