Have you tried talking to him about it?  I know some guys are just dense (that whole one track mind thing!) and don't notice these kind of things unless they are held up to their face :)

I change my sons diapers all the time.  I actually wanted to, to bond with him.  But I have MANY male friends who insist on not changing diapers, and their wives are okay with it.   This is because they talked first, and came to an agreement.  Its called being and adult. 

Please ignore the suggestions of putting crap in his car, letting diapers accumulate into a hazmat scene, etc.  Tit for tat never works long term...just look at the middle east.   You may succeed into forcing him to clean poo off his car seat, but then he will realize you are insane and he will find a way to get out of the situation - ie...he will leave you.  Tit for tat is how you end up divorced and alone.

1) Recognize that you both succeed or fail in this together, 2) talk to your husband 3) if he wont do diapers, maybe there is something else that he can do that will help take the burden off you.   4) if you still dont get what you want, suck it up, you have a child to think about.   Your children will be the victim of your scary mommyness because they understand your tone and your actions toward your husband very well.   it shapes how they view proper relationships, and they will treat their future partners just as you treat you husband.  

Find out what your husband CAN do and reward and praise him for that.  If you find he really truly cant do anything, well....you married the guy and had a child with him, what were you thinking?

bracing myself now for the flaming hate mail..

My DH didn't do poo diapers. He just couldn't handle it. But having said that, if he was on his own with them he did change them - he wouldn't let them sit in it (he used to tie a small hand towel around his nose and mouth LOL). So if I was home, I did all the poopie ones which was just fine with me. 

I agree tit for tat is not a way to go, but @alh10 , you are doing an awful lot of things that any grown man should be able to do on his own (I.e. laying out his clothes, making his lunch, making his dinner plate, etc). To me, those are things that are done to show appreciation and are not necessarily part of every SAHM's 'regular' duties...I think if he can't pitch in on his off time (seeing as how YOU don't get any) you could sit him down and calmly and rationally explain that those extras are just too much on top of all you do. If he doesn't want to help with the baby that is fine, but you can't handle two babies at once so he needs to take those extra duties off your hands. Then kiss him sweetly and point him in the direction of the closet where he can find his own damn clothes.

And @sanedaddy, (and this is an honest question and not a sarcastic one, because I can't figure this out for the life of me) why should a wife have to reward her husband for taking care of his own children? I understand praising and saying "I really appreciate that, thanks baby", but I know a lot of men who expect rewards (usually food or sex) if they do normal things around the house like dishes or cleaning.  Where does this idea come from? Women do these things all the time but I've never heard a women say "I'll take out the trash if you spend an hour downtown tonight"...

Speaking as a father of five - he should be changing diapers.  If he isn't changing diapers, has he picked up more household duties?  Does he do he laundry and put it away, doe the dishes, vacuum the floor?  If you two are doing this together, then there will have to be give and take, otherwise you will get stuck doing everything and that will not turn out well in the long run.

Remember, they get out of diapers in two years (or so), but they will always throw up - if he can't handle a little crap, I am sure you will be stuck cleaning that up by yourself as well.....address it now sanely before it all piles up to the point where you can't take it anymore.

Well said, @Happy_Jack!

This is crazy.  I would kill my husband.  Not ok!