Cornell:
2014 - Feb 28. Last week of Feb, Friday
2013 - Feb 25-26. Last week of Feb, Monday
2012 - Feb 27-28. Last week of Feb, Monday
2011 - Feb 23. Last full week of Feb, Wednesday
2010 - Feb 23. Last full week of Feb, Tuesday
If I was a betting man, I'd wager we should hear from Cornell today or Friday.
To your second question, some schools have an internal waitlist. A stack of people they don't want to reject but they for whatever reason don't publicize their waitlist. As such it could still be a rejection or an acceptance but you might not know for a bit. I doubt that they have not looked at your application prior to sending out notifications of any sort, but I may be wrong. It seems to vary greatly by school.