I've contemplated this a lot, actually. I still might do it sometime, although I just moved from a city of ~150k with bountiful surrounding public space to a giant metropolis of 5 million and endless sprawl. So I think that complicates things a bit... I'm here building up my stache and living with SO who is in grad school, so van life might be more plausible a few years down the road.
Check out
http://www.cheaprvliving.com/ if you haven't already, it presents a fairly romanticized view of van life but with a lot of practical tips included. The guy who runs this site was also featured in the documentary, which is available on youtube, called "Without Bound"
Also, If you can find it, check out the book "Walden on Wheels". It's about, among other things, a guy who lives in a van while attending grad school at Duke. It's a pretty entertaining read.
I think about doing this a lot but haven't had the courage to take the plunge yet. I wonder if it would be feasible in a parking garage, of which there are plenty here in the city...