Seagate will soon be bringing out a new batch of server hard disks. Using the smaller 2.5" format, and featuring a very impressive two million hour Mean Time Before Failure (MTBF), the new 600GB drives are said (by Seagate) to be about 20% more reliable than comparable offerings available. Besides that good MTBF rating, you also get a five year warranty from Seagate for these drives.
These drives spin at 10k, and will be available in both 450GB and 600GB configurations. You'll also have the choice between 4Gbps Fiber Channel, or a 6Gbps SAS interface.
No word yet on the price of these new HDDs.