Jeff Lamarche author of the book “Beginning iPhone Development” has written (and is currently writing) a . He does an incredibly job of simplifying the complex ideas behind working in 3D and makes learning OpenGL ES easy for even a novice programmer.
I have always struggled with OpenGL as 3D has a lot of nerdy math, this series breaks it down into the simplest of forms and helped me tremendously. So go check it out and let me know what you think.
Jeff is also on Twitter