Just 15 minutes ago, I just rebooted my MBP 15" with its new Seagate Momentus 500G 7200 RPM 16Meg cache drive in place. It is working quite nicely. I had changed out the drive in my old 13" Alu MacBook before it was stolen, and I had noticed a bit bit of a speed increase...at least I think so. Loading big images into PS CS4 seems a hair faster. We'll see. Havent done any before tests, so it'll be hard to quantify. Anyway, its the space I wanted.
Anywho, they are on sale at Best Buy right now for $109, which is same price as at NewEgg amazingly....