The talent Pursuit of Justice, in the first tier of the paladin tree, reads you gain 15% movement speed, and an additional 5% for every stack of holy power you have, one you use an ability that consumes this holy power the speed goes away.
The exploit is, rather then using the holy power just allow it to fade, and the 15% movement speed that you get from having the holy power, does not go away
leaving you at 130% movement speed on foot