Floating cities? Legalizing marijuana?

I came across an article on cnn.com today about the possibility of a floating city within the next three years. They have a prototype and believe it is something we will see very soon. The first floating city they plan to make is going to be off the coast of San Francisco Of course this idea is intriguing in its own, but the part that sparked a debate in my mind was experiment with different forms of government on these cities. One idea the article brought up was legalizing marijuana. While I think it is a good thing to see if they may be better forms of government to employ, the pessimistic side of me thinks that this will cause problems between the "mainland" and the "island". How will people be able to draw the line when these two separate forms of government are located so close? Does any one else see that this could be a problem?

http://www.cnn.com/2009/TECH/03/09/floating.cities.seasteading/index.html