We'll definitely see quad core in iMac and eventually laptops. It's not a question of "if", it's a question of "when". Consumers are doing things like video processing, music, etc that can use plenty of power. And the high end laptops and iMacs are really positioned as pro (or at least semi-pro) machines based on price and performance.
Well, they seem to be selling $2249 iMacs now. But I do agree that it would be nice to see them use desktop components and deliver quad core for much less.
Check this out, they could be offering this in an iMac right now if they were willing to use desktop components...or in a midtower:
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115017