I'm a first year MD/PhD at Dartmouth. The admissions office wouldn't still be interviewing (until March 27th I'm told) if there were no chance for an acceptance. They just have a ranking system where every candidate who is interviewed is assigned a score and people with a score above a certain value are accepted outright. They keep moving the score necessary for an acceptance down as the season goes on. If your score is low enough that they don't think they'll move the acceptance level enough this year, you're rejected (and this rejection level moves up as the interview season goes). Some people with scores between the rejection cut-off and somwhere below the acceptance threshold are waitlisted. If you haven't heard anything yet (or have been waitlisted), you may very well still have a good chance of acceptance but the score assigned to you hasn't quite been in the acceptance range yet. So, don't lost hope. Also, it's important to know that people get off the waitlist. MANY of my classmates were accepted off the waitlist, some as early as May and one (a great guy) as late as the first day of orientation.
So, don't lose hope! Also, I'd encourage those of you who are waitlisted (or who haven't heard yet) and who are still very interested in coming to Dartmouth to show your interest to the wonderful people who work in admissions (we really do have an amazingly nice and dedicated group of people working in admissions). Send updates, LOIs (if appropriate), etc. It can't hurt....
Also, if you have any other questions (about the school, the area, etc.), please feel free to post them or PM me.