An interesting article appeared in Wired a few weeks ago: Soccer Embraces Big Data to Quantify the Beautiful Game. It discusses the use of the Adidas MiCoach SPEED_CELL in the MLS draft games. The device contains an accelerometer and a GPS (although the commercially available version doesn't have a GPS; I've got one).
Basically, you get a players speed, and potentially position, displayed on an ipad on the sidelines. You could also derive various real-time statistics, they discuss a "power" metric. They suggest that football would be more popular in America if they could statistically quantify what is going on. Apparently Americans love their stats: RBIs, free-throw percentages, yards gain, and all that.
I'm pretty interested in real-time analysis of player and team performance. I'd be interested to know how much data is used in real-time by managers/coaches, I suspect almost none. I'm not sure how much value it could add to in-match decisions, but making yourself more likely to "win" by a few percent could be advantageous over a whole season.