This is definately one of those things where I think there should be distinctions. I never bought into the whole "two become one" thing with marriage (even though that's how my marriage became). I say like two become two, because two > one.
If you only have one income, then obviously you would be sharing the incomes and the money would be equally for each of you.
But in either case, I think that each partner should have their own account and their own money, and then a joint account for bills. I think contributions should be such that all the bills get paid, and then each partner is left with the exact same amount of spending money.
And since I'm not a big credit card kinda guy, you should keep one tucked away somewhere for emergencies only.