There are people who do this solely as their own business but it helps to be tied into a larger home builder. From what I understand, the forms are quite costly and you need a steady diet of similar homes to pay for them, something that a large scale builder can easily provide. In our area, you don't typically find the smaller concrete operations who do driveways, walks, etc., doing poured walls, just because of the cost of forms.
I did have an independent bid the walls for my house and they were a little over $2k higher. Now, that being said, given the cost overruns I hit straight out of the gate with having to go more courses in my garage and having to bring in a pumper trailer, I may have eaten through the savings!
As far as the weather goes......not looking so good for this week as it is going to be pretty wet with no real sign of a good freeze or dryspell for the next 10 days.