I did this upgrade this past weekend with my 15" Unibody Macbook Pro and two WD 320GB 7200RPM drives. The speeds I'm getting out of this thing now are ridiculous. I'm getting anywhere from 2 - 3x performance gains, depending on the read write size. Obviously, this doubles my chances of drive failure, but I'm enforcing a strict backup strategy for data recovery.

I would recommend this to anybody that has to work with large files on a daily basis. In my case, I run a Windows VM constantly on my MacBook. It makes reading a 80GB VHD (partitioned into 2GB chunks) a lot more snappier.