Here is a bit more detail in terms of the methods they are using.  It aims to watch for changes in brightness with certain stars:

Among the methods astronomers have used to discover extra solar planets, the most successful is a technique called transit photometry. It measures changes in a star’s brightness caused when a planet crosses in front of its star along our line of sight.

Astronomers using NASA’s Kepler Space Telescope have employed this technique to become the most successful planet-hunting spacecraft to date, with more than a thousand established discoveries and many more awaiting confirmation. Future missions carrying improved technology are now in the works.

How much can they tell us about alien planetary systems similar to our own?A great deal, according to a recently published study. It shows that in the best-case scenarios, these upcoming missions could uncover planetary moons, ringed worlds similar to Saturn, and even large collections of asteroids.

What do you think will we find one or more planets very similar to Earth?

thanks to SpaceRip for the great info