Last night The Trust For Public Land presented a movie about the other Portland (Oregon) and it's urban growth boundary. Clip: http://www.youtube.com/watch?v=avNmiHnSXns
Even the most progressive planning can run into hurdles as Portland did when their land owners outside the boundary led and passed a referendum to get rid of the boundary and let them maximize their profit on their land.
The key is to build in mechanisms when drafting growth boundaries which automatically diffuses tensions which build up from time to time. Just like catastrophe theory, when grains of sand are allowed to build up, a tiny avalanche eventually happens.