The iGDK helps to create new games and port existing games to the iPhone and the iPod touch.

Here is its feature list:

• Core
  • OpenGL ES 1.1 support with extension handling
  • Math library that supports fixed-point and floating-point calculations with an interface very similar to the D3D math library
  • Support for numerous texture formats including the PowerVR 2-bit, 4-bit and normal map compression formats (hardware support for those is not exposed so far)
  • Support for PowerVR’s POD (Scene and Meshes) and the 3DS files formats
  • Timer support with ms precision
• Input
  • Touch screen support
• Camera
  • Polar camera model (as a template to implement something more complex)
• Displays messages and Icons on Screen
• Utility
  • Logging functionality that stores the file name, source line, time and the log entry in a file during run-time
  • Memory Manager supports
    • Heap walking
    • Memory pools (generic / non-generic)
    • Memory bookmarks
    • Hierarchical heaps
    • Memory leak detection
• Resources
  • Resource streaming system

• Planned features:
  • In-game profiler
  • Render target support
  • More advanced camera models
  • Input manager
  • Portal system
  • kd-tree support
  • DOOM III map file format support

-> http://code.google.com/p/igdk/