WD Caviar Black 1TB is the fastest largest consumer drive that WD makes that I know of. It's based on the same platters as the WD640. Haven't heard anything about larger than 1TB drives yet.
I know Seagate has a 1.5TB scheduled for release relatively soon, and Hitachi announced their plans for 1TB+ capacity drives for the future as well. No word yet on WD and 1TB+ drives.
But speaking from personal experience with two WD6400AAKS's in RAID0 for 1280GB of advertised space, it's pretty sweet.
1.5TB drives will be out from Seagate in september. They will not be offering an enterprise sata version of this drive however. In may of 2009, the 2.0TB drive will be released.
Except the WD Black 750 GB and 1 TB are way overpriced. WD (from what I see) changed very little, renamed their drives, then raised the price tag by 30%. Way to go, WD.