NASA's Kepler Mission is dedicated to exploring the universe on the hunt for habitable planets.  The Kepler project launched in March of 2009, and consists of a very awesome telescope which finds planets based on the "habitable zone" of a star.  

A star's habitable zone is the swath of space in which a habitable planet might exist.  Earth obviously is square in the middle of Sol's habitable zone.  Too far out and you're too cold to easily support life, like the icy Neptune.  Too close in and you're molten hot, like Mercury.

Kepler is going to be watching for the transits of planets across the face of their suns.  This gives astronomers more information about the planets, because of a technique that can be used to determine the composition of the planet's atmosphere.  It also lets them know more about the planet's orbital habits - a planet which whips around the sun too quickly is not as habitable as one which transits at a comfortable speed.

It used to be thought that there were very few Earth-like planets in the universe.  (And if you go back far enough, it's all God's fault.)  But recent calculations have shown that habitable planets are probably a lot more common than we originally thought.  Of course, "habitable" doesn't mean "inhabited by intelligent life."  It may not even mean "inhabited."  Think of Mars, which is almost habitable (except for that pesky thin atmosphere and shortage of useful water).  But it is certainly not inhabited.

Even if we find planets which turn out to be inhabited, they may not be inhabited by anything with which we could have a reasonable conversation.  Human intelligence is a fairly recent innovation for Earth; until our reign came along at the tail end of our planet's history, Earth was perfectly habitable, and inhabited, but only by insects, animals, birds, plants, and so forth.

The main difference between the Kepler telescope and other super telescopes like Hubble is that those telescopes were designed to see a very small section of space.  They had tunnel vision.  Kepler, on the other hand, is designed to see broad swaths of space, which will definitely help in the ongoing search for planets.  

The Kepler mission is named after early astronomer Johannes Kepler, who lived in Austria in the late 1500s and early 1600s.  Kepler was a major player in the scientific revolution of the 17th century, and developed two theories of planetary motion which are now known as "Kepler's Laws."

Kepler was born to a father who made a living as a mercenary, and a mother who was a folk doctor (and was later tried for witchcraft).  Kepler was brilliant although sickly, having been born prematurely, and having survived an attack of smallpox which left him with diminished vision and reduced use of his hands.  

Kepler revolutionized astronomy with his two laws.  The first law defined a planet's motion as an ellipse, which solved the problem of so-called "retrograde movement."  (If you're on an elliptical path, and you observe something on a different elliptical path, there will be a point where the other object will seem to be moving backwards.  This confusion lives on in the "Mercury in retrograde" superstition.)  The second law essentially states that all planets move at a steady speed.