there haven't been any D2 or D2G updates since their releases that are to any serious significance. So it really cant be known yet. The devices are quite similar so the ROMs aren't that different. But they are different enough to specify them as different updates to different devices. So i would expect to see the D2G updates roll out about 2-3 weeks after the D2. I only assume the D2 gets it first because of how similar the ROMs are to the Droid X.