after you interview, all interviewees are then evaluated (based on interview dates) for acceptance. once you go through the entire evaluation process, you are either accepted or "waitlisted". so by now, if you haven't received an acceptance, then you are in this "waitlist", which contains all the interviewees minus the 150 or so that have been accepted so far. also, im like 99% sure that we don't have a ranked waitlist. everytime an opening comes up, all of those on the waitlist are re-evaluated.
those of you still waiting, hang in there! i didn't hear back until mid-may (and i would say a significant portion of my class were the same), so UCLA definitely has a decent "WL" movement. it is a long and tough process, cause i have classmates who didn't hear back until like early july, but trust me, it'll be worth it