Thanks for the link! Luckily, from what I've seen of our weekend rides, this shouldn't be an issue for us, since by that point we generally ride single file. Actually, I'd be fairly hard pressed to think of many times I've seen groups riding more than 2 wide there, but I guess it happens occasionally.
This sounded cool too, which I didn't know about: "MacArthur Boulevard is scheduled to get wider shoulders and an 8-foot-wide shared-use hiker/biker path along a 7.3 mile stretch from Old Angler's Inn in Potomac to the Washington, D.C., border." If the path there wasn't covered in road grit all the time, I'd ride it more often.
Another heads up - as I was biking out MacArthur & Falls yesterday, a police officer was taking photos of cyclists heading down Falls from MacArthur and another was sitting at the Clara Barton ramp on MacArthur. I'm not sure if it's related to these plans, or a response to complaints, but keep an eye out.