Jim,
Tell the inquiring runners that the marathon course has been measured to approximately the same extent to which New Orleans has been rebuilt! It's true that I've been over the proposed route one time, and so far we have 25.05 miles. The distance isn't going to be a problem, as there are possibilities for adjustment at both start and finish. The DC portions of the course are fine, for the most part, although I must add that it wasn't any fun to measure through the Ninth Street tunnel, and I don't expect that to be one of the highlights of anyone's race either. As for the Maryland portions, let's just say that improvements would be welcome. Of course if the whole road, or one whole side of it, is closed down completely for the race, then the course might look a lot more welcoming than it did to me.
For now, that's about all I can tell you. There's a lot more work ahead. Maybe I will put in a request to have winter cancelled this year.