This issue was brought up, with regard to ServerFault, nearly three months ago. At that time, Jeff responded:
We will do this, but I agree with Michael -- there's not enough data yet. Plus, we'd like to "perfect" the process with the SO data dump before extending it to the other sites.
Check back in a few months...
I'm not sure what "enough" data is precisely, but I think that the need and rationale given for creating the data dumps does not depend on the quantity of said data. And given the fact that there don't seem to be any major issues that have cropped up, I'd say that the process seems to be more or less "perfected".
Finally, now that it's almost 3 months later, I would like to formally request that the September (and all future) dumps contain data from all four sites (SO, SF, SU, Meta).
One thing that does come to mind to address when creating the dump for all the sites is to provide migration information - perhaps additional fields in the posts table:
MigratedToSiteId, MigratedToPostId for the origin post and
MigratedFromSiteId, MigratedFromPostId for the target post? Is there anything else that needs to be tweaked/added?
edit: Just remembered something else that should go in the dump - account association information. This will help keep track of users' activity across sites, and since it's already public info I don't think that there are any privacy issues. However, it's not clear to me what the ideal format would be, especially if the sites will be in their own separate dumps. What makes most sense to be is to have a table with the user IDs on the different sites as the fields i.e.:
<row StackOverflowUserId="658" ServerFaultUserId="548" SuperUserUserId="6" MetaUserId="658" />
for all users with accounts on 2 or more sites.