Christ, you guys are negative. I guess it's different in every field, but last year when I applied I received my last rejection letter in May, and 2 schools didn't even bother to send me any response at all! Really, just because your schools have sent out some acceptance letters, they definitely haven't sent out all. Usually applications are grouped into definite yes, definite no, and then a maybe pile. Those in the yes group get the first wave of letters. The no group might receive rejection letters right away, or they might wait until all the positions have been filled. The maybe group gets put on a waitlist and those people are picked as the need arises.