Monks are Psionic. (Yes, “Martial Striker” was half wrong). As per the Design & Development article that accompanied it, Ki is a dead power source (though some third party products have already tried to use it). Personally, I have no problem with this. On multiple occasions, I attempted to run campaigns with an eastern flavor, and banned most (or all) arcane and divine classes, relying primarily on psionic and ki powered characters. Conceptually, they always seemed very close together: an internal energy source with fantastic abilities powered by intense discipline.