I am sure everyone is aware of the latest release of exoplanet data from Kepler that has multiplied the number of known exoplanet candidates by a factor of about five. Kepler detects its exoplanets by looking for stellar transits so it is only going to see them in the rare cases where we are in alignment with the plane of the stars planetary system. Luckily it can look at a lot of stars in a patch of the sky all at the same time. In its first few months it has found well over a thousand by this method. Some of these may prove to be glitches and must be verified either by land-based observations of by repeat transits observed from Kepler.
So which is the most Earthlike planets they have seen? To answer this you need to peruse the full set of data which can be found here. Even then the answer depends on what you consider to be the most important parameters to define an Earthlike planet. After due consideration I am going to go for Keplar-268 which has an estimated radius of 1.75 times the Earth, a year of 110 days and it sits at 0.41 astronomical units from its parent star. This should give it an estimated surface temperature of 295 degree Kelvin or 22 degrees Celcius. Admittedly it is a bit large so its gravity is going to be stronger than we would probably enjoy.
The estimated temperature that NASA uses is based on the amount of received radiation. I’m not sure if there is any correction for greenhouse effects which depend on the density and content of its unknown atmosphere. In any case it is at least reasonable to assume that its rotation will not be locked to its star so it has a chance of being habitable with liquid water present. On the other had it’s high gravity may mean it retains too much atmosphere and suffers from permanent clouds making its surface very hot and high pressured.
This is just the first big release of data from Kepler and more can be expected, especially since many Earthlike planets will not have done a full revolution of their star in the time it has been l0oking. The results so far suggest that when all data is collected there should be some candidates for really Earthlike planets, at least in terms of size and ambient temperature. Once their location is known it will be the job of other telescopes to look at them in more detail. This will include the best Earth-based telescopes using adaptive optics and interferometry to focus in on the systems. A little later the James Webb Space Telescope should take over, if and when it successfully reaches its position to start observing in space.