Yes, it can be much better. I'd been waiting for it with anticipation ever since Intel announced these chips about 3 weeks ago and ordered one yesterday.
Need to remember, clock speeds can only be compared within the same line any more. There are a lot of other things that go on to making CPUs faster.
1. The instruction set is going to make it faster than any C2D at similar clock speeds.
2. It is a hyper threaded chip - meaning it will process 4 threads in comparison to the C2D 2 threads.
3. It has turbo boost up to 2.9Ghz for additional power when needed.
Notebookcheck.net would be the place to see Benchmark scores. They don't have them yet, the chip is too new. Their initial placement of the i7-2677M has it ranked at 57th place, while that C2D is sitting at 134th.
Benchmark's don't tell you everything about CPUs, and Geekbench is probably the worst of the benchmarking tools, they'll give you at least an idea.
Here's one for this new 1.8.
Here's one from last years MacBookPro 2.8 Ghz hyper threaded chip.
Now
here are some scores from last year's C2D MBA.
Compare for yourself.
