The carpet cleaners came today. The large, nasty spot in the middle of our living room is gone. Neither of us have any idea what it was or when it appeared, but we are both thankful it disappeared! The other choice was replacing the carpet (about $1350 more) or arranging the furniture to cover it up- which would have looked quite odd in that room!
Next up, list the house with the realtor and this move will officially get underway!