I'm betting chemistry, not life. But Carl Zimmer's report of a press conference suggests researchers are seriously thinking they may have evidence for life on Mars.
We'll see. People have gotten excited about this twice before that I can recall. Once in the 1970s, after Viking landed, and again in the 1990s, when people saw some suspicious things in Martian meteors. Neither panned out.
Additional: The research being referred to is here, with the decidedly low-key title, "Strong Release of Methane on Mars in Northern Summer 2003."
More additional: The Bad Astronomy blog looks at headlines related to this story. Annoyance ensues.