We all know how hard life can be, but spare a thought for the microbes recently discovered 1.6 kilometres (1 mile) below the seabed off the coast of Canada. The living conditions are cramped, the environment is a searing 100°C (212F), and yet these hardy cells appear to be thriving. In the midst of the historic landing of Phoenix in the arctic wastes of Mars yesterday, the interest in finding life on the Red Planet has, yet again, reached fever pitch. Although Phoenix isn't built to look for life, it is assessing the Martian surface water content for signs that it may (or may have been able to) support life.
That last sentence is crucially important considering that we sent two craft capable of searching for extant life in 1975 . . . and have yet to duplicate the feat despite access to better technology and increased understanding of the planet itself.