It absolutely depends on the yoga! I've taken yoga classes that were intense strength training all by themselves. I would not be able to do an effective resistance training routine on the same day. However, if it's more of a slow, relaxing yoga, then there's no reason you can't do it on the same day as any other exercise.
35 lbs. lost from 1/04/10 to 5/29/10
Size 14 to Size 8, 41-35-44 to 38-28-38
Maintaining Size 8, 39-29-39
Striving for functional fitness!