I'm within 10 lbs of my weight at my first prenatal appointment, so I figure I'm pretty well off in that respect. I gained 40 lbs during my pregnancy, and a week later I had lost 15 of it (of course, 9 of those lbs were a baby). Three months after giving birth, I had lost everything, and it seems sometime between now and then I have gained back 10 lbs. But I'm really not worried. I fit in my clothes for the most part, and I'm doing what I can/need to to provide my baby with nutrition he needs. I figure I've got 4 more months of breastfeeding and then I will have a full-fledged walking toddler so I can incorporate that into my weight-loss plan.
Then again, if anyone saw me and heard me say the words "weight-loss plan" they would probably throw punches. I'm 5'4" and a very thin frame. I've just got a small spare tire around the middle, but I think I read somewhere that (as a result of evolution, as a holdover from the caveman days) when you're nursing your body keeps fat in reserve in case YOU can't get food so that you would still be able to provide for the baby.