technically, foveon is superior. but that's just in theory, in practice it is still not up there overall (mainly in terms of dinamic range and sensitivity, iirc). the resolution argument is bullshit, one must understand the bayer sensor resolution is (partly) a lie, as it is interpolated, foveon claims of 14mp at 2640x1760 pixels is based on the fact that you can interpolate to upscale the image, and get the same image, as sharp as a 14mp bayer sensor (which is reasonable, as most people these days think in terms of bayer-resolution, so foveon must relate to that, to be able to market their product).
sigma has been using foveon for years (more than five, btw), and they are more cramed in their niche market than pentax or olympus are, for instance. let's hope they will get out, and the technology will mature, but i doubt pentax can afford to back this untill it is mature (nikon, otoh, could have, and maybe should have)
just my two cents