The Spitzer InfraRed Space Telescope, launched a few years ago, has , more or less by accident found the remains of – not one – *but two* rocky planets around a star about 100 light years away.
The two planets, one estimated to be in the order of Earth sized, the other Moon sized , appear to have collided probably a few thousand years ago, very recent in astronomical terms.
More detail can be found at Bad Astronomer Blog
This is, as far as I know, the first, however indirect, evidence of Earth/Moon sized planets.
That is not all : A few days ago it was reported that the Kepler Space Telescope, launched this year, had detected the atmosphere of a planet orbiting another star
Exciting times indeed.