Not necessarily, with the lower end chips in particular the real world performance difference isn't exactly huge and the TDP will likely remain exactly the same as the previous generation.
The high end machines will benefit most - there's no question a mobile i7 quad core will be easiest the fastest Apple laptop ever and the flexible clock speed should help power saving too.
The lower end i5 (and I guess potentially i3) machines not so much, they won't be quad core and the performance benefit over current dual core chips likely won't be very big in the real world. They also lack some of the more advanced power saving features of the top end i7 chips.
Basically, if you were thinking of buying a top end Macbook Pro 15" then it'll be a big thing. If you were looking at a 13" mid range machine then don't wait expecting some huge performance gain out of the refresh.
