They're getting closer...
This is a plot of the extra-solar planets discovered so far, plotted by mass and orbital distance from their suns, and comparing them with the planets of our solar system.
As this diary points out, with the new Kepler orbital telescope in action, it won't likely be long before planets very similar in these properties to Earth will be found.
Will they call the first planet so found Caprica? Vulcan? Trantor?