I just bought myself a 2TB White light after reading the manual and seeing the section on creating RAID mirror, however, it appears that 2TB drives come in a single drive edition, like the one I've got, and it cannot be mirrored. You are stuck with a single 2TB volume. Reading the manual more carefully now, My Book World Edition are single drive, which cannot be mirrored. My Book World Edition II are dual drive systems that can be configured as RAID. Actually checking on Western Digital's site, the World Edition II is not yet available, so if you are after RAID 1, you will just have to wait, until Western Digital release them, or you'll have to stick with the Blue Circle drives, if you can find them.
I'm quite disappointed, because I was after a drive that could be mirrored, after one of the drives in my blue circle drives died. Guess I'll have to make do with this one, and try and find a backup solution for the 2TB volume.