I'm tempted to throw away arcane and divine magic and run a homebrew world with psionics and incarnum.Wooooo! Mo' power to ya! :)
(But seriously, this is a really good idea!)
WaterdhavianFlapjack
My own homebrew d20 Dungeons and Dragons setting is built around Psionics as the first and natural supernatural power available in the setting. Magic and Arcane / Priestly magic comes in later in the history books and is often considered "unnatural" or "evil".
In my campaign psionics is not described as "psionics" so much as persons perception of what psionics might be. In one culture a psionic character might be a gifted priest, blessed by the saints with the ability to perform miracles while in another culture it might be viewed as a form of witchcraft...people in my setting get burned at the stake for "witchcraft" wielding the same psionics that the uneducated followers of the "holy orders" believe are the blessings of the saints.