I knew some SCSI fiend would show up eventually. Anyway, ...
Keep in mind that the we are currently in the first generation of SATA. The advantages, right now, appear to be minimal. Thankfully, SATA performance is just as good as ATA, so early adopters aren't seeing a drop in overall performance. As the second generation of SATA nears, there will come some more interesting features, as well as a speed bump across the interface. Hot-plugging and hot-swapping will allow users the option of powering down and removing drives while maintaining system integrity and uptime. NCQ/TCQ support for efficient transfers should make systems feel a little smoother. Daisy-chaining will allow users to have fewer SATA ports, but support more devices. (Daisy-chaining is a good reason why the speed of the interface will be numped up. Sure, a lone device may not max out th allowable bandwidth. As you add more devices to the same controller, you'll need that extra headroom.) Finally, using the common interface between SATA and Serial-Attached SCSI will ultimately eliminated special cables for this device and a different cable for that device. We will finally be able to use one cable standard regardless of the technology behind it.
-SUO