i was wondering the same. i guess it depends on what u will be doing. i figure to get up early and follow an intern around does not lend itself well to wearing a suit 🙂 did u ask the program?
I actually asked one of the chief residents what one would wear, and she said that you should wear whatever you normally do on your rotations. So, for guys a shirt and tie would be fine. A white coat was not necessary (though you might want to ask about that directly, in case the program requires that you do wear one).