I just got a 250GB Seagate barracuda 7200.8, and have 2x120GB 7200.7s (early .7s without NCQ) all SATA. All the reviews i have read said that there was very little difference between the drives, and from a performance point of view there really isent any noticeable difference.
From a temperature point of view though the 7200.8 runs so much cooler.
I had the 7200.7s running in the open air on my desk, and the 7200.8 in my case, where things tend to get hotter. The 7200.7s are really quite hot to touch, DTemp reported them at 46C and 47C (and no I didnt leave them in the sun or by a radiator), while the 7200.8 felt warm, DTemp reported 36C. I was really quite shocked by the difference - 10C.