Henry
Autoexreginated
By and large, it won't matter if it's an ability or not; from what I'm gatehring from the dispel magic preview, there aren't going to be very many "ability counter-abilities" the way there were in 3E. In other words, it won't matter if it's a power or not, because you won't have anything that can interfere with it. In the cases where you DO interfere, such as that Fighter's Combat Awareness thing, it's spelled out pretty clearly.