Dec. 5, 2011: The first habitable Super-Earth is discovered in orbit around a sun-like star (close, but way too big to be considered "Earth-like").
Dec. 20, 2011: The first Earth-sized exoplanets are discovered (although we don't yet know if they are terrestrial planets like Earth, or gaseous like Neptune).
And just today, two separate paradigm-bending stories:
Will the announcement of the first true Earth analog, a terrestrial planet located in the habitable zone of a star more or less like our Sun, occur in 2012?
Like many others, my guess is yes, it will.