Some sound, (if somewhat grumpy) advice from someone in the industry here:
http://www.soundbrew.com/small.html - despite the at-times discouraging tone, makes some salient points about the amount of effort vs. payoff, both in terms of job satisfaction and cash flow. The fun parts of brewing (brewing, recipe formulation, experimentation)
will lose some of their charms when brewing on a schedule for customers and those 'fun' parts will only be a small percentage of the time you will spend cleaning and maintaining the brewery and running a business.
There is no way around the fact that brewing professionally is extremely capital intensive (and from talking with pro brewers, breweries eat money), and volume-driven, so plan for success and build-in the capacity that will keep your customers happy and keep you from burn out. Not trying to be a downer at all - I love the passion of American entrepreneurial vision and hope many of the nano-picos do very well and increase the quantity and quality of American beer, but it's a huge challenge.
I've spent the last year or so do fairly extensive research with a partner into opening a brewpub and I can say it's been an ehem, 'sobering' experience to learn all that goes into making our romantic hobby a viable profession. While it's still a dream of mine (a nearly complete business plan that will continue to be tweaked), it's been put off for awhile down the road when we're better equipped (read lots of $$$$), to enter into it better leveraged and with eyes wide open.