xBench disc speed comparison on my unibody 15" MacBook Pro before and after replacing the 5400RPM WD5000BEVT with a 7200RPM ST9500420AS. Pretty impressive, though the speed increase closely correlates to the current price difference on Newegg. Weirdly, the new drive seems quieter. I can't comment yet on heat or battery life effects.
P.S. Changing the drive on these machines is like taking a bath in warm kefir - so easy.