The German Democratic Republic is alive and well, and better than it ever really was, in "Good bye, Lenin!" THESE DAYS IT IS HARD TO TELL that Berlin was a divided city. There's hardly a trace of the Wall left, save for a block strip. On Potsdamer Platz, once known as a no-man's-land with concrete barriers and barbed wire, there's a Starbucks, McDonald's, and an Eddie Bauer. In the heart of the platz is the Sony multiplex theater. On my trip to Berlin last December, "Finding Nemo" had just premiered there, complete with a red carpet and an after-party featuring...