The idea of never punting/always going for it on 4th down as a strategy has been floated around for a few years, first (at least that I'm aware of) in this paper by David Romer:
http://elsa.berkeley.edu/~dromer/papers/PAPER_NFL_JULY05_FORWEB_CORRECTE...
And then further discussed in this post on Football Outsiders:
http://www.footballoutsiders.com/stat-analysis/2006/never-punting
As commenters noted, NFL coaches, being a very conservative bunch relative to a guy like, say, Mike Leach, won't try it but maybe someone in college or high school would. Well, someone has, and even taken it farther -- not only do they not punt, but they almost always attempt onside kicks, don't bother putting a returner back on punts, etc. Here's the article:
http://sportsillustrated.cnn.com/2009/writers/jon_wertheim/09/17/no.punt...