And the latest says that a planet does not even have to have a sun. It could be a wandering rogue planet and still have life.
http://news.sciencemag.org/scienceno...li.html?ref=hp
As to where they all are, keep in mind that the earth has had multiple major setbacks in lifes progress to reach this point. If there is life fairly nearby then they might very well be far ahead of us. They might consider us for a visit as we would consider a nest of rattlesnakes.