As embarassing as it might be, I've found that discussing my mild stuttering problem with other people in my life does help grease the gears of the social interactions. There can be misconceptions that arise about ones intentions or character, when this isn't done. In a presentation before an audience, however, I think it's very common for ordinary people to get nervous and stutter... and so you might actually find that it wouldn't be necessary to begin your presentation with this announcement. As much as each of us would curl up and die inside as we block during a speech, audiences might overlook the problem altogether.