Hmm, I probably should have made a partition for it. I'm going to go out on a limb and say I can't retroactively do that without screwing around with the partitioning. I can probably degrade the array, create a new volume group, and slowly move files around until I can eliminate the old group and the old PV. Think that's a good plan?
It's definitely LVM2 on Arch Linux. It's not a terribly old installation - about two years. AL tends to be a fairly bleeding edge distribution, which is part of why I'm migrating away from it. That was great when I had fewer responsibilities and could dedicate more time to screwing around with my computers. These days, however, I have college work, a job, and a girlfriend. I find that I want something less bleeding edge, friendlier to leave with my parents back home, and easier to leave alone for long stretches of time.
Thanks for the help!