It will work the same as if you plugged in more than one hard drive into the popoplug.
I have one partitioned into 3 separate ones. I use one partition as a redundant backup of files I may never need, one for files I may need but not often and one for files I access often.
If using the drive app in multi-drive mode they would show up as drive Q,R,S, etc. If using the drive app and not multi drive mode they would show up as folders under the "P" drive.
On My.pogoplug site they show up separately as whatever you name the partitions looking like separate drives.

Place Shifting Enthusiasts