do you know if there is a software that uses this GPU on a non iphone platform?
SGX is currently shipping in a number of phones, netbooks and development boards other than the iPhone. I believe there is a fairly complete list on wikipedia here:
Because of that Wikipedia list, I have to ask: Is the OpenGL ES 2.0 SDK for iPhone 3GS also useful for the 3rd generation iPod touch (32 GB and 64 GB)?
OpenGL ES 2.0 is exposed on the later iPod Touches - I believe the two models you mention are the correct ones for use with this API.