With further use I've found that the hot swap hard drives show up in Dolphin just fine, even if they aren't mounted manual.  It must have been just the first time after formatting that they don't appear, whereas with fdisk, they do.

For those that aren't aware a hot swap capable motherboard (and BIOS) + 4 bay (or more) trayless hot swap cage = heaven !  It brings a whole new level of ease of use when it comes to hard drives.