It's the thread that keeps on giving! http://news.ycombinator.com/item?id=2639456

If brown dwarfs and giant wandering planets are as prevalent as we think they are, then there's almost always a port of call for humanity only 2 LY away for large swathes of the galaxy. If we can figure out how to create "seeds" of our civilization that are reasonably compact, we can send them across that distance in only a couple of decades using laser sails and other propulsion schemes not limited by the rocket equation.