Yea that's what I was gonna say. That and there won't be Octo-Core in an iMac for a long time. Gotta separate the "Pros" from the "Consumers." Expect an Octo-Core iMac when either:
A. Hell freezes over.
or
B. 16-Core MacPro gets announced.
I see it this way, if we're lucky:
August/September 2008: New iMacs, top-end is quad-core (because right now prices are very close to dual core processors, and by then they will be smaller, mobile, and cheaper)
2009: Quad core iMacs again.
2010: Quad core, with high end eight core possibly, but not likely.
iMacs wouldn't use two processors, how would they fit in the casing (which by then should be much smaller) and the cooling would be a nightmare. So, until eight core processors are widely released and cheap (maybe 2010, but probably not until 2011/2012) it ain't happening.