For certain operations yes, but the thing to note about a core is that it contains everything a processor thread needs; an ALU, vector units, etc. etc. A single core running multiple threads may not be able to allow both threads access to some resources simultaneously, for example if both threads try to do an add, they would both need access to the ALU.
Even accounting for these potential "clashes" though I suspect that there will be quite a good performance bump, I doubt it's anywhere near the theoretical double though!
Here's what the tech-specs say:
[quote="Apple.com]Next-generation Intel microarchitecture
8MB of fully shared L3 cache per processor
Integrated memory controller
Turbo Boost dynamic performance (up to 3.33GHz on 8-core 2.93GHz system)
Hyper-Threading technology for up to 16 virtual cores
128-bit SSE4 SIMD engine
64-bit data paths and registers
Optimized for energy efficiency[/quote]
I've highlighted one bit that interests me; it seems as though the processors can still achieve 3.2ghz or higher speeds, but possibly only for short bursts.
