We have one son-2 years old, another baby on the way, and while we have a good thing going now: i get out early (5:45) and am back home by 7 so my wife can get an hour walk in while i feed my son breakfast and get myself ready for work. it's a challenge, but it seems to work., and i still get to work on time (being the boss helps...)
i don't know what we are going to do when the new baby arrives, but i presume it will still mean i'll be up and out early, and i'll probably cut down on the training for a little while. on saturdays my wife sleeps in, i get upowith my son, and when she gets up, i head out for my run. for sunday long runs i alternate going to a training partner's house or he comes to ours-we do this at 7:30 at the very latest, as he has 3 kids, himself. 3 hour marathon training runs are hardest-these take the most negotiation, but its workable.
Finding the time is definitely a challenge, but with negotiation it can work. I, too, give up sleep and am in bed by 9:30 at the latest.
finding that extra time is tough, but i am finding that as the weather gets better, my son is amenable to the baby jogger more and more-even first thing in the morning during the week-if its an easy day-giving my pregnant wife extra time to sleep, relax, whatever, (that i can then use for negotiating purposes later on...). he's also been known to fall asleep in it, and i'll run until he wakes up, which gives me at minimum 70 minutes. another thing we've done is do running errands while he is in the baby jogger on saturdays-pick up bagels, the newspaper, drop off a video, and although the intensity isn't great, i can get a lot of miles in and be on my feet fo 90 minutes or so while being with my son and still be fresh for a long run the next day. add in some hills with the baby jogger and its not a bad workout.
good luck-i am curious about how you got your miles in when each of your kids were first born....