I'm honestly not too optimistic. Keep in mind that the 8800 is the BTO 'upgrade' card, not the standard - what Apple has done for the past two major generations of iMacs (the last set of white ones and then the aluminum ones) is bring out a new generation with a mediocre card (the x1600 in the whites, the HD 2600 in the alus) without the option for an upgrade. The next revision then introduces a decent GPU as a BTO option in the high-end models (last time it was the 7600 GT, this time it was the 8800), presumably partially as a carrot to get existing iMac owners to upgrade. If they choose to follow this pattern, we can expect the next line to have a middling GPU across the board (something like the 9600 or the 3600) without a high-end option until the next revision.