Well, the title says everything... How many earth-like planets have we discovered out there? Discard too big (made of gas), too cold, too hot, etc. Consider earth-like sun distance, size, temperature, the rocky ones...
Twelve plus Mars are considered as potentially habitable (as of February 10, 2014).
The question was whether there were any "Earth-like" planets, not whether any were habitable. I believe the answer is currently, not very many.
Of the 31 (as of 6th Aug 2015) confirmed potentially habitable planets most orbit K and M-dwarfs and are much closer to their Sun than we are; all are probably bigger and more massive than the Earth. There are 3 that orbit G-type stars: tau Cet e, Kepler 22b and Kepler 452b, all are thought to be at least 50% bigger than Earth.
So it depends how far you are prepared to stretch your definition of "Earth-like", but I would say there are about 3. Kepler 452b is the only one with an orbital "year" greater than 300 days.