Mobile GPU cards were tried for a while, but it died out very quickly. Given how much power these GPUs use, it's going to stay that way for some time. At the moment there are two technologies which might get around this.
At GDC a couple of weeks ago, OnLive made an announcement about cloud gaming. Essentially their servers run the game and your laptop/pc/console plays back the video output. Theoretically sounds great, it can run on even low powered netbooks, but it remains to be seen whether they can resolve lag issues between the controller and the action appearing on the screen. At the moment, the cost of such a service hasn't been published.
The other technology, which has been mentioned for a fair few number of years, is having an external dedicated GPU housed in a box. Originally Asus announced they would be doing this, http://www.bit-tech.net/news/hardwar...notebook_GPU/1
, but nothing ever became of it. AMD developed XGH (an external PCIe bus) but so far only Fujitsu have a released one laptop supporting this (http://arstechnica.com/old/content/2...ght-of-day.ars
). I think this sort of technology is truly promising, it allows your laptop to be powerful enough for gaming when at home, but still portable enough for other uses.