Looks like Star Trek and science fiction in general were right all along - There is a planet at Alpha Centauri! Astronomers announced it today, though I wish they had come up with a better name than Alpha Centauri Bb. Unfortunately, while the planet has about the same mass as the Earth, it's too close to its Sun to be of any use.
Imagine if it wasn't though, if it was in the right orbit and habitable? The human race would have a reachable goal to set its sights on. True, at four light years, it would take far too long to reach it by conventional means, but it could be the motivation mankind needs to push itself. We could set up a globally-funded science organization to work on building generation ships and the best, fastest propulsion systems possible, while working on making relativity and physics as a whole our bitch, and invent an FTL system.