To those who haven't heard a thing from schools,
Do not despair. At least not yet. Here is why:
1. Although this does not happen often, it is not unheard of candidates being accepted at different times. For example, this year, somebody was accepted at the Comp. Lit. Program at Northwestern in the end of January and another applicant was also accepted just three days ago. So you and I could be next.
2. The fact that you have not yet heard anything also means that they have not yet rejected you. Most likely, by this time, no answer at least means that your application might be still considered for waitlist.
3. The waitlist is a real possibility. In fact, applicants who are accepted at places such as Cornell or Yale are likely to get accepted in more than one school. They can only choose one of course, and that means that some folks in the waitlist are bound to get accepted.
4. Some applicants do get accepted with great funding at a much later date than mid February. Looking at past years I noticed that some people found out by late April that they got in the school they dreamed of with great funding.
I guess that's all. But enough to be optimistic eh?