Some folks (myself not included) believe that at least some of the governments of the Earth have been in contact with them.
Discussions of whether or not there should be "disclosure" by governments on the existence of extraterrestrials always boils down to a question of whether or not we, as a society, are ready for such news. Often cited is the idea that religious people in particular would completely freak out.
Personally, I'm inclined to believe that we, as a culture, ARE ready for such an announcement, were one coming. The majority of people (something like 60% IIRC) already believe in extraterrestrial life already.
That does leave a question though: Is there room in religion for aliens? What would the implications of the Gospel be with the knowledge that there are other living beings in the universe?
My personal opinion is that nothing in the LDS Church would change, except that maybe we'd start gearing up to send missionaries to other worlds
