An interesting article:
"Dick Kerr of Science magazine, who's been writing planetary science a good bit longer than most of us in this game, has a remarkable story up on the Science Now site -- something potentially far more striking than the crossbedding announcement. The team on the Mars Express Planetary Fourier Spectrometer (PFS) has announced the discovery of what look like methane absorption lines in the Martian atmosphere at 3.3 microns. Kerr quotes the PFS principal investigator, Vittorio Formisano saying it's "A very little amount," -- 10.5 parts per billion -- "but the result is clear." If this is indeed methane, then it's evidence that something is going on: either volcanic activity or life."