It appears that decisions trickled in over a span of several weeks last year...another applicant received his decision during the last week of April in 2010!
For those that are seriously considering other programs requiring decisions by 4/15/11, I suggest you call admissions to reiterate your dilemma and also ask to speak with the Admissions Coordinator or Director of Admissions to discuss your situation. If they are unable to connect you (I'm sure they are inundated) request them to kindly forward yoru message - I'm sure this will encourage them to send out decisions sooner than later.
I also suggest that all of us call next week again for updates to encourage them and also post updates on here!
Thanks and enjoy your weekend!