The idea that life came to Earth from somewhere else (or moved in the other direction) has been floating around for a while. From what I gather its kind of out there as theories go. We know rocks from Mars have made it to earth and vice versa. But if life could have gone with them well thats rather more complex. The evidence for water on Mars in the past is now quite compelling. And in the frozen state in the present we also know that from the various space craft that have beens sent there.
Of course it does make great late night TV.