What is the point when drives aren't even hitting 1.5Gb/s, and they definitely aren't even coming close to 3.0Gb/s?
Just an internal speed rating, the electronics are capable of doing 3.0Gb/s, although the drive isn't able to, it may have an effect on the actual throughput of the drive even though physically it's not hitting the electrical limitation.
We also have no boards to support such technology yet and being the x58 was just released, I think we are a little off from having it anyways. It will be good as we continue to need faster drives, comparatively speaking drives have gotten much larger than faster.
Notice how a Raptor 10k Sata1 loses in burst speeds to a decent 7200rpm Sata2 drive, even though the speeds are not breaking the 1.5Gb/s rate.