I've heard from UMass Amherst, UConn, Northeastern, and Northwestern. I'm taking my post-bac classes at UMass now, and know that they do a sort of rolling admissions. They accept their top choices early on, and as people decline, they accept more people. So it is a combination of rolling admissions and a waitlist, though they don't notify you of waitlist status. It's possible that they could continue to offer admission until the end of April, after the response deadline. Don't give up hope yet!