I don't think people realize just how much of an advantage this could have been for the Pats. Teams don't change their signs for every game due to a high probablility of confusion and an increased probability of blown coverages leading to easy scores for the offense. The Pats could have been video taping the signs in the 1st meeting for use against division rivals in the 2nd, and also could have employed a "scout" team to tape the next weeks coming opponent. This is a huge development that has people questioning calls going back years and leads to questions like this one from the Cowboys site:
"Dylan Falkenburg, Wells, Maine: Just wanted to get your thoughts on the two amazing blitz pickups in the Bill vs. Bill game back in 2003. When I watched this game I was ready to bow down to the Patriots' staff as the greatest play-callers of all time. Two big blitzes from the Cowboys, and two incidents of perfect blocking assignments being called. Two big plays, leading to two scores. Have I been duped? Is Belichick just a cheater?
Mickey: You know, now that you mention this, I remember that well, how the Patriots seemed to counter the blitzing Cowboys with screen passes thrown away from the blitz. Seemingly every time. And I was with you back then. But now, this is what happens when someone's credibility is called into question, just as the NBA recently went through with referee Tim Donaghy, everyone going back to games he worked and calling into question some of his calls. This is why Roger Goodell's punishment must be swift and harsh. "
To me those are all legitimate questions now and the benefit gained by cheating could have been huge for their entire SB runs. This has to shake the NFL to the core much, much worse than the Michael Vick problem.