This is my first year as an RA. I know quite a few resident assistants who got into medical school. Personally, I don't think this type of thing will receive recognition until an interview. One thing I have learned about this job is that everybody has an EXTREMELY different experience. Not only from the personality of the RA but the composition of the floor residents. For example, I have a 34 year old undergraduate on my floor. Nice guy! Interesting history (not medical history, sorry, I almost forgot I was on SDN...).
Point is...It helps, but only if you really can talk about it. In other words, adcomms will tell if you are enthusiastic when they ask you about it. If you had a pretty bad experience as an RA, chances are 1) it wont be in your personal statement, and 2) you won't talk about it much at the interview. If you had some great leadership experiences, you'll really stand out.
I'm still waiting to have some of those experiences. RA's at my school tend to be more "leaders" when they work in all or mostly-freshmen dorms. I work in a dorm which houses very few freshmen. So my experience is a little different, but I'm coming back next year and we'll see if things change.