Well, lots of people, given the popularity and the recurrence of that question on the forums. So far the answer for an iMac, iBook or eMac is still a firm no.
However things could change. NVidia introduced a prototype of a replaceable video card for laptops.
The interface between the logic board and the video card is based on PCI-Express. There would eventually be 3 variants corresponding to the graphic card's power consumption. The first PC products carrying this technology should be ready by the beginning of the fourth quarter.
Apple could certainly use those upgradable cards in a few of its products. Changing the graphic card in a Powerbook or an iMac is quite an appealing idea.
Now, it all depends on the will of Apple to offer upgrade paths, which would go against the current policy of replacing the machines rather than upgrading them.
