There was talk on a parallel thread about the use of the ATI 4870 graphics cards.
It now seems like this may be even more plausible in the upcoming iMac, as now Leopard 10.5.7 has kernel extensions for the ATI Radeon HD 4000 series of graphics cards
Is there a 4870M? If not, then forget it.
Also, Nehalem is also mentioned, but I doubt we'll see them in the next iMac refresh
Of course not.