That implies 4/7ths of the planets in the galaxy are "Earth sized."
no it does not imply that, with the short time Kepler's been going now, they can only have confirmed planets in orbits very close to their star. Closer proximity to the star means stronger solar winds, to name but one of the many possible reasons why there might be a stronger tendency towards smaller planets close to the star, as opposed to further out.. (just think of the line-up of our own solar system for that if you like... other than Pluto the small ones are all in the centre, and Pluto is not really "part" of our planetary system anyway since it's on such a weird orbit all of it's own it seems it might just as well be a captured object from a different system..)
Brain off-line, please wait.