UNC selects 30 total waitlisted applicants (15 in state and 15 out of state). Those who are selected for admission and waitlist are sent letters after the committee meets (which this year was Feb. 4th)
Unfortunately, from what they told me, is that if you aren't contacted or mailed a letter on Feb 9th (the day they mail out all their letters) and informed that you were selected for admission or put on the waitlist, then you are not being considered for the 2004 admissions cycle and they will mail you a letter in april to inform you that your application is expired for that cycle. (You can verify this on their website under admissions timeline)
Sorry I couldnt give you better news....
If you want to verify this info you could call the school yourself and have them tell you...but i am almost 100% sure
Good luck....have you heard from other schools?? or applied to others??