I think Glenn Beck as talking about that theory on his radio show. Our government was denying it (naturally), and I don't know of any way to independently prove or disprove it. I think if it were a missile launch, enough pilots would have seen it and enough people would have seen it on their radar screens that it would have been pretty hard to keep it a secret.

Meteorological conditions support the contrails theory though, and the rule of Occam's razor suggests that is the most likely explanation. But we'll likely never know for sure.

Onward and upward,
airforce