The Method Baby & Mom post Natal Yoga with Gurmukh Khalsa, avaiilable at Amazon.com. It's kundalini yoga, a live shoot of a class...absolute chaos with moms and babies all over the place. It's great! I used to get all stressed out when kids interrupted my yoga practice, but after watching these moms deal with their babies in the middle of a class (nursing, crying, whatever) I have a new attitude. As I recall, you start by doing some yoga with your baby laying on the floor, then gradually incorporate them into the practice. Towards the end you massage them and focus exclusively on them. BTW, kundalini yoga looks alot different then some other types -- it looks a bit like calesthenics interspersed with meditation. Gurmukh's focus is on reclaiming your navel center, which is the power center of your body. So expect *alot* of belly work!
Things I've read and heard indicate that you should wait until 2 mos. postpartum to resume practice, although I think it depends on how quickly you heal/stop bleeding/etc. (which took seemingly forever with dd#2).