I'd wait till 2010 and see what Apple does with the MBP line, which are likely to be using these:
Intel To Launch New Mobile CPUs In January
I went by Best Buy to look at the quad-core HP Envy and the thing was insanely, insanely hot just idling (way hotter than my MBP has ever gotten, even when going full bore). There's a Dell quad-core laptop that it looks like Calkwalk is endorsing pretty highly, so maybe that one runs cooler, but I'd at least wait and see if/how Apple competes on that front.