Ok, it's no secret that GPUs are rather powerful and can do more than run games in Modern gaming consoles and PCs. It can speed up various processes such as video playback for common users and for more advanced users, cracking encryptions. Developing programs to take advantage of this also is not very difficult thanks to the development of OpenCL. However, the majority of programs that use GPU acceleration either don't need it, or are heavily unoptimized.
The best example I can make is the current beta of Firefox 4 as it has GPU acceleration. Despite not using very much processing power, it still will make GPUs run at maximum temperature. For desktops this is not a major issue, but for laptops this is VERY bad as most of these programs fail to account for that. Furthermore, the difference with GPU acceleration enabled and disabled is minimal at best on any halfway decent processor with multiple cores. It's examples such as this that show that in many respects GPU acceleration is unnecessary and actually a bad idea when it is not optimized.