NASA's Kepler Mission team announced the discovery of over 700 potential exoplanets. The list of newly discovered exoplanets includes about 100 planets that are two to four times the size of Earth, but what's causing some controversy is that NASA chose to withheld information of about 400 objects until February so as to confirm these are not false positives and to have priority in publishing on the exoplanets. The 400 withheld targets are likely to be the most interesting planets, as these objects are smaller than 1.5 Earth radii.
Today should be a historic moment for the field of astronomy. With a single data release, the team behind NASA's Kepler instrument has nearly doubled the number of extrasolar planets we're aware of, including many that fall between the sizes of Earth and Neptune, a class of planets that was poorly represented in our existing collection. Instead, NASA's handling of the announcement appears to have been very confused, and attention will likely focus on the candidate planets that were left out: 400 objects that are even smaller than the ones being announced.
The decision to hold back on the most Earth-like objects had been made months ago. The intent is to allow the project scientists the chance to confirm these are not false positives and to have priority in publishing on the exoplanets. These candidates are mentioned only once in a draft paper that describes the data that is being released. Referring to Earth's radius as Re, the draft states, "those [stars] with the small-size candidates (ie, those with radii less than 1.5 Re), are among the 400 withheld targets and are thus not among those considered here."