Don't start about the naming scheme for their notebook parts:
http://www.notebookcheck.net/Mobile-...ist.844.0.html
The naming scheme seems to have no baring with the desktop parts!! The GTX260M basically has nothing to do with the GT200 series as it is basically an 8800GT based on the G92 core.
Lets look at the renaming in more detail
1.)8800GTS 320MB and 8800GTS 640MB - G80 core(65nm,96 shaders,384mb bit memory access)
2.)8800GTS 512MB - G92 core(65nm,128 shaders,256 bit memory access) to 9800GTX(same core) to 9800GTX+(65nm and 55nm,same core) to GTS250(55nm,same core)
3.)8800GT -G92 core (65nm,112 shaders.256 bit memory access) to 9800GT(65nm and 55nm,same core) to GT240(same core for OEM)
4.)8800GS -G92 core(65nm,96 shaders,192 bit memory access) to 9600GSO(same core) to 9600GSO G94 core(48 shaders,256 bit memory access)
There are some other rebrands around but I cannot be bothered to list them all.