@tolleranza - I am trying to figure out when to go public as well. The best advice I have read thus far is that when you can start to show significant annual increase in revenue and you would like to seek outside investment (as opposed to asking friends, family or trying to secure the ever elusive small business loan) then you are likely ready to be ready to go public.
I also found out that you do not have to go through an initial public offering! I did not know this. I do not know the details of this strategy, just that it is an option.
Also there are companies that specialize in taking companies from private to public; therefore I am thinking about finding out what they think is a must before going public.