In the "for what it's worth department," when I was waiting to hear from Master's programs it took them until late April to make decisions, because they always make decisions on PhDs first. Now that I'm applying for PhD programs, I'm finding out that the wait time isn't much better. I contacted my top choice school and they said I should expect to hear from them by Mid-March even though *multiple* people have already been either accepted or rejected. Same thing with my second choice.
Oftentimes when a school does not contact you, and you see other people have received both positive and negative results, it means that you have been "secretly waitlisted." Many top schools will not bother to notify you of this status unless you contact them directly. I applied to a total of seven schools. My current status is accepted to a very high ranking program that was in my "mid-range," rejected at a second program in my mid-range, wait-listed at my third choice and on the "silent" wait list at my top two (meaning I had to call to find out). The bottom two (which include the school I currently attend) haven't even *started* the process yet. So, the bottom line is that no news is good news. It means they aren't willing to let you go quite yet.
If you *do* find out you've been waitlisted, consider sending a letter thanking the school for continuing to consider you and letting them know any new achievements you've made since your application was sent out. Remind them why you're such a good fit, etc. Think of it as a second, revised letter of intent. Also, consider sending an additional letter of recommendation that helps to flesh out your qualifications. Do NOT do this if you have been directly forbidden (obviously); however, in all other cases my professors tell me it helps to remind the school of your dedication, etc.
Best of luck everyone!