Rammus goes faster during Powerball. Unlike almost every other ability in the game, the tooltip for Powerball doesn't specify how much of a speed increase Rammus receives. Mobafire, Leaguecraft, and SoloMid don't appear to have specifics available, either.
Does the ability in general increase your movement speed by a percentage, or a flat amount?
Is there any credence to the hearsay I've encountered which indicates that powerball ignores the soft caps on movespeed?