I was at Best Buy last week and asked sales rep if the Photon would be able to work with the current Atrix laptop dock and he said no, but that there should be an update that could get it to work since the Atrix and the Photon are essentially "the same phone." He didn't say anything about a specific dock coming out for the Photon though.
From the pics I have seen, the Photon and the Atrix are not aligned at all with regard to their USB and HDMI ports. Both are used to dock the Atrix, so I would be surprised if there was an adapter of some sort to use the Atrix laptock with the Photon.
Maybe they could come up with a way to remove and replace the 'door' where you dock the phone; that would seem to be the only way to 'adapt' the Atrix lapdock for the Photon.
It's really a shame that Motorola took this approach, because they could have increased the market for the lapdocks significantly by making the accessories (lapdock, Media dock, car dock) cross-compatible with both phones..