Here's my progress report. I've been going to the gym quite a bit recently -- 3-4 times a week for the last two weeks. My routine goes: Stretch lower body for ~10 minutes, run 2 miles on the treadmill + cooldown in ~20 minutes, then I spend about 45 minutes to an hour on weights. I'm @ 12.9% body fat now, down from 15% two weeks ago. And I must be building some muscle, as my weight hasn't changed substantially. Maybe a pound or two lighter -- maybe not. I'm close enough to my original weight that any changes could just be typical fluctuations in my body's water-content. Anway, Yay! I still have a long-way to go to get back to the body I had just before Maddy was born, but I've at least got something of a start.
I've decided to try p90x after all. I just ordered a pull-up bar. I'm going to try to do the program with my wife. I've been going to the gym, but my wife doesn't have (nor can we afford) a gym membership (mine comes with tuition - no opt-out option). And she doesn't have the motivation to exercise on her own. Currently, after 8 hours of work/school, and then spending all evening entertaining Maddy, we're both kind of emotionally drained. She usually watches TV, and I usually end up playing on the computer cos I'm not very interested in TV (until Jon Stewart comes on). I figure, if we do it at 9pm every day, after putting Maddy to bed, it'll actually give us something fun to do every night together. Stacy's been saying how much she'd like to get Wii Fit and how she thinks she could get herself to do that cos it'd be kind of fun, but I just suspect that the physical benefits of Wii Fit are probably pretty inconsequential. Plus it's $100.
At any rate, I imagine that with us doing this together every night, it's going to end in sex more frequently than going to separate rooms to do our own solitary, sedentary activities. So that'll be even more exercise!

I've only glanced at the nutrition stuff. It looks like there's a lot to read and plan. Hopefully it is no more expensive than what we're already doing in terms of meals, or we'll probably have to cut corners on that part of it. But we'll see. I've gone down 2% in body fat in just 2 weeks and all I've been doing is being somewhat more mindful of portion size, and forcing myself to not eat a fourth meal before bed (tip: drink water when you get urges to eat and you know you shouldn't -- people commonly mistake thirst for hunger). Have a big glass of water and see if that doesn't satiate you far longer than you would expect).
Good luck! None of this is difficult or miserable stuff. It's just staying disciplined. Here's hoping we all succeed.