I think what Sony has shown, they are the only one who is working towards a FX mirror-less camera. I think Panasonic and Oly would be poised for a FX version but they don't have the capital to dump into developing a completely new system. They seem to be content with the m4/3 and for good reason - they are eating the low Dslr market like a kid in a candy store. Nikon and Canon could be working on something, and I think MSmoto is right, the mirror must go at some point, but for now the best AF and Metering utilizes the mirror. I think Nikon's J1/V1 shows that they know this as well, that AF is fast - but still not pro DSLR fast.
I think the better question for a mirrorless is not who will produce a FF one, but when the quality of the smaller sensors will match the quality desired, and when will f1.0 glass be or the technology be available to achieve the bokeh as well.