Depends on the schools. Some schools put the requirements on their web page with the dates they will accept. If the school you want doesn't, I would suggest you call the ones or better yet email the schools you are applying to and ask them.
I applied for class 2008 with the MCAT I took in August 2001 with no troubles. I could have applied to some schools this year as well, but not all of them. So check to make sure.
Good luck.