There was a time when you couldn't get anyone to "travel" to Brooklyn from the city to hang out. People would turn up their noses and act like you'd invited them to visit you in Timbuktu. Now everyone is clamoring not only to hang out here but to live and work here as well.
I've lived in Brooklyn for 15 years (had to sneak that in!) and never has it trumped Manhattan so thoroughly as it does right now (ipso facto I am uber cool). This may border on blasphemy to some, but in ways "the city" seems passe. Take, for instance, the decision to have the Brooklyn Museum host the Jean Paul Gaultier retrospective in October 2013. In the past, Brooklyn would never have had a shot at hosting an exhibit that has already drawn over 500,000 visitors. But times are changing.
Don't let the door hit you on the way out, Manhattan.