Odds of finding life on Mars

When I first read about the "Big Belch" on Mars, in the Sun of all places, I was a tad incredulous. Turns out however that the evidence is pretty tantalizing. But short of going there and digging we won't know for sure. What do you think are the odds that the origin of the methane is biotic? Turns out bookies have stopped taking bets since the discovery. In the 1970's the odds of finding past or present life on Mars were 1000:1, and before the discovery they were hovering around 16:1. Bookies however are still taking bets on whether life is still present on Mars at 500:1 (seems like a good bet to me), and whether president Obama will announce the discovery of intelligent extra-terrestrial life in this current year, and the odds are 66:1 (seems like a bad bet to me). Gentlemen, time to make your bets, comment with your odds and the wisdom of the crowd will enlighten us.