I just installed and formatted a 2nd internal 2 TB SATA drive for my Mac Pro (i.e. occupies Bay 2). Followed the instructions here to format. I now see it when I take a look at my whole setup (Go/Home), so that seems okay.
However, when I started Lightroom 3, it does not detect the drive, i.e. I see only my Mac HD as before (I have also asked this question on Adobe's forums in case it is a Lightroom problem).
Thanks for the follow up question. This was resolved on the Adobe forum.
For any lurkers: Lightroom does not recognize a device unless it has a catalogue item in it. The solution is to Import a photo (and then it does include the device in the library). Thereafter, the device -- in this case the 2nd hard drive -- appears in the lefthand column of the Lightroom Library. Files can then be manually dragged from one hard drive to another without resorting to Import.
Sadly, just after this, my new Mac Pro had a kernel panic fail. Not sure what that is related to but, after a long conversation with Apple, it's going back to the store for a complete diagnosis. Probably nothing to do with this particular issue, though. 😟