Three Russians, a Chinese, a Frenchman and an Italian walk into a simulation chamber...and don't come out for 17 months.
That's pretty much the idea behind Mars 500, which starts tomorrow and aims to be the highest-fidelity simulation of a Mars mission ever conducted—as well as the first to last as long as an actual round-trip to the Red Planet. Inside a multi-cylinder chamber on the Moscow campus of the Institute for Medical and Biological Problems, six volunteers will spend 520 days doing the things real Mars astronauts are expected to do: running experiments, growing plants, communicating with Earth (with a true-to-life 20 minute signal delay), exploring the Martian surface (okay, another module), and generally seeing if they can get through without cracking up or committing homicide.
Follow the mission at this Russian site created in cooperation with Google (but with sometimes sketchy English translation). There's also plenty of information at the European Space Agency Mars 500 site, and video clips at this Russian-language YouTube channel (why "Moon River," though?).
For a quick orientation, watch this ESA video: