SATA has the Raptor, and now 8-device RAID 5.
For single- and dual-HD 1U servers, the Raptor is great, in a hot-swap bay, yummy goodness.
For workstations, it gives a fantastic value compared to SCSI.
However, it hasn't been proven in constant DB work (and won't be until SATA II).
OTOH, you're looking at your new Opteron. Quad 844 now, get dual-core when it comes out, 8-16GB RAM...you're at $10,000 before you hit the storage system, OS or software. SCSI is a known good quantity. Why bother with risking anything else?
Last but not least, SAS will make SCSI cable pricing a thing of the past. Plain old SATA cables doing all the work. Easy to route, only 20MB/s potentially lost, in theory, and there's other goodness. Read up on it.
...if SATA *does* kill SCSI, all it will mean will be that we'll have SATA Atlas, Cheatah and MA? 20k+ RPM SATA drives.