Last time we went (about 3 - 4 years ago) the "boundary" thing had to do with alcohol. If you read your packet, they state in there that you must not bring beer/wine etc with you and instead must purchase it at the event (for about $25 a case, no less). You are only allowed to drink those beverages in your "defined area" - in other words, you're not supposed to walk around with a beer in your hand.
Of course I don't know many teams that bought those cases of beer, and no one ever came around inspecting coolers in the 5 - 6 years I did the event, so I don't know what all the fuss was about. I think it has to do with sponsorship and city ordinances and such.
But the DC event is fun - there are a LOT of people that come through there both days, and there is a LOT to do. It's the only remaining event where they close down Pennsylvania Ave, and they want to keep it that way (hence all the regulations).
Load in/Load out is a real
bi!@h, and the turnins can be several blocks away.
As others have said, bring plenty of power cords. 100' would be a bare minimum for me (same with hoses, if they let you hook up to water). Staging in for loadin can be tough - we generally parked on one of the side streets that ran perpendicular to Penn ave, and waited there. Parking is tough, and we opted for the paid parking sections in one of the underground lots. More secure than the open air parking.
Watch out for vagrants and such. They're everywhere, and the DC police have their hands full with them. They'll steal anything that's not tied down, especially during the initial loadin and loadout, before the barricades are up.