Two items on the cheering speech front:
First, I am quoted in today's New York Times on the subject, staking out my favored position that it's all First-Amendment protected and at least state-run facilities cannot do much. This subject seems to be back in the news of late, helped by some high-profile incidents, such as the eviction of former NC State basketball stars Tom Gugliotta and Chris Corchiani from an NC Stage game last month. The Times interview was pretty interesting, because the reporter seemed dubious and so, apparently, were the other people he had spoken to.
Second, here's an example of when cheering speech can be pretty clever: Fans of a lower-division German soccer team that had not scored in several game brought a sign reading "We'll show you where the goal is," then another group stood behind the visitors' goal holding yellow and green arrows and pointing them at the net (click to enlarge). Deadspin has video of the fans in motion. Now should the team, upset by the fans' "negativity," be able to stop this quite clever (and non-disruptive, since there aren't many people at the game) expression of dissatisfaction with the team's performance? And if the answer is no, then we need some way to draw a line between this and booing and yelling that the players stink--and no one has ever successfully drawn that line.