Being a Mac fan myself I think it's sad that Apple stays too far behind the technology curve. Right now 2 cores is most you can get in their portables. For those like me who regularly run virtual machines (VMWare Fusion) 2 cores just doesn't cut it, come on Apple we need 4 cores. Having 4 cores allows me to run 2 cores for the primary O/S and 2 cores for the VM O/S. And for those occasions when 3 VMs are running at the same time having 4 cores is an absolute requirement. The difference in performance is night and day. Windows laptops have had quad cores for over a year now. While I'm on my soapbox, Apple you really need to start offering blu-ray drives as well.
The mobile core i3, i5, i7 are all still only dual-core (besides i7-720QM/820QM).
Those dual-cores do have hyper-threading, but it's not the same as having 4 individual cores.