"Graphics acceleration is where a piece of software (e.g. a game) calls a standard OpenGL routine (to calculate and draw a particular 3D vector, for example) and, rather than the main phone processor having to do all the sums long-hand, the built-in graphics hardware, built from the ground up for this sort of job, leaps into action and does the work in a fraction of the time.
The end result, for the user, is that many games (e.g. Oval Racer, FIFA 07, Quake, Global race, Crash Bandicoot, Panda Manda, Knights of the Dark Age, to name a few) run smoother and faster, videos play back with no glitches (handling a wider range of resolutions and bitrates without stuttering) andgraphics-heavy applications run without problems (e.g. Mobitubia, the YouTube client can play back videos smoothly at the same time as downloading them as fast as possible). "