I was referring to apple products. What other manufacturers do is irrelevant as far as this thread goes. If you're talking about Macs (this is macrumors, and the OP is trying to decide on which MBP) and discussing purchasing options of Quad core vs Dual, then the fact that apple don't make a small quad core machine is relevant.
That processor has also been out for only a couple of months., and I will wager that it is not available in the sort of volume apple shifts MBAs at.
Handbrake fills all 8 threads on my MBP 15". As does quicktime X conversion, and a number of other CPU intensive tasks. This trend will only continue. Apps that can't take advantage of multiple threads will adapt or be replaced by those that can - clock speeds aren't going to be going up much faster, the way ahead is more cores.