Yeah, a single state, especially Connecticut, banning assault rifles does nothing because there's no border guards between states and you can trivially drive to 10 other nearby states to buy a weapon if you wanted.
The point you're missing is that the weapons used in that shooting were legal to own in Connecticut under the existing "assault weapons ban". They were not transported from one state to another. Part of the point of the article is that such bans are meaningless because there is no actual functional definition of an assault weapon. A point that a few of you seem to have completely missed.
Edited, Jan 3rd 2013 1:34pm by gbaji