My favorites and ones that I reach for continually are Hilary Burnett's Intermediate Pilates, Winsor Pilates Advanced Body Slimming, and either of Jules Benson pilates workouts.
One of Jules is nearly an hour, but she has a shorter one that's coupled with a step workout (I only do the pilates portion) that's only 20 minutes and is just basically a shorter version of the longer one.
Oh,and also the new 10 Minute Quick Sculpt Pilates (as previously mentioned earlier) is a great little workout. Tougher than the other 10 minute ones in its own sneaky little way.
Terri