I think that the trick to organic lawn care is to alter your expectations a bit. From what I've seen, it's really tough to have a weed free lawn using organic products. If weeds are a major concern then the organic route may be a short trip to frustrationville.
The really great thing about the organic method is that it encourages you to focus on the soil. Anyone who has done some gardening knows that there is almost no substitute for good soil. The major problem that arises relative to organic lawn care is that most developed residential areas have had the "good" soil removed when the houses were built. It's not always the case, but if you live in the suburbs, you may be fighting a serious battle against the condition of your soil. I've read that some homeowners who jump into the organic method with both feet will actually kill off the old lawn and till in a few tons of compost and good soil. Then they replant the grass and basically pull a fresh start on the whole thing.
One intermediate step would be to heavily aerate your lawn and then spread a lot of compost-type topdressing. This will filter down into the soil and add organic matter/nutrients to your soil