Don't be so dramatic... No really. Yes it is serious business but the world isn't ending. I you are selling your product on a regulated market place you can keep track of your own income and figure your own taxes.
Whats all this about people running lemonade stands getting in trouble? If you have a booth at the fair or a stand in down town that you operate all summer then yes you should pay taxes. But little kids? Being sued? Questionable...
It is always good to be aware of the law and the how it applies to you but if the majority of the time it is not something you need to fret about. If Stencyl Forge gets a market place it will be entirely legal. You will most likely have to send in a tax form like on Kongregate and that will be it.
Out of curiosity what country are you from Grim?
On topic: I would really like to see rep points of some kind integrated into the Forge. That way when we have some awesome contributors they can be recognized, and quality products more easily found. It could be based loosely off dls, ratings and mabey some other criteria.