Effectively, yes. We've seen it rather handily demonstrated several times, in fact. We know that Unicorns all have a magical 'knack' for a certain spell related to their talent. This is canon. We have seen pegasi circumvent the laws of reality in order to do something related to their talent. It really only makes sense that
E Ps would therefor develop a similar 'knack' for their given talent. In some ways one could say that all EP's are low-level psychics of some manner or another, in usually very specific fields. Sometimes that ability manifests itself parallel to the talent itself(In Pinkie's case and likely Big Mac's as well; his super strength may come from subconscious telekinesis), and in some cases the knack manifests for such a talent that it appears to be a standard psychic ability.
Ponies like Pinkie and Mac are the Earth Pony equivalent of Twilight: Extraordinarily powerful, in a more broad or even holistic fasion.
Of course were one to chicken-and-egg it, I believe the talent comes first. The CM is probably the magical manifestation of one's acceptance of their knack, and serves as a reinforcement loop - Their powers excel with belief, so they bestow themselves with something that fosters belief and, therefore, keeps the power strong.
edited 3rd Jul '12 7:11:39 PM by kegisak