Something interesting (I think) surfaced today on ipforce.jp (I used google translate):
??6515452 | ???????IP Force? Camera equipped with contrast AF function
"As described above, according to the present embodiment, in the single-lens reflex digital camera 10 having the photometric sensor 20A and the distance measuring sensor 18A, phase difference focus detection using the distance measuring sensor 18A and contrast using the photometric sensor 20A Formula focus detection can be selectively performed by user setting. Further, even in the case where phase difference type focus detection is set, it is possible to switch to contrast type focus detection when it is difficult to determine the in-focus state by the phase difference type focus detection for the subject characteristic and the subject area.
[0060]
By selectively setting two focus detection methods, it becomes possible to set focus detection methods suitable for various photographing situations. And since contrast type focus detection is performed using photometric sensor 20A provided in connection with exposure control, a problem of parallax does not occur.
Furthermore, it is possible for the user to confirm an object image and its area in focus using the optical finder, and to perform contrast AF processing without discomfort while performing the same shooting operation as a conventional single-lens reflex camera. Can. Furthermore, since the photometric sensor 20A for detecting the brightness of the subject is used, it is not necessary to provide a circuit such as a new imaging element."
Basically, if I understand it right, Ricoh has put a small sensor inside the pentaprism housing that can perform contrast detect AF while user is using the OVF, and it can work somewhat alongside the standard PDAF module below the mirror.