We are ISV Partners and all of our packaging orgs have been upgraded to Winter 13. One of the features of Winter 13 was supposed to allow us to push major release versions to subscriber orgs. I would have expected it to be in the previously existing "Push Upgrade" section of our packaging orgs, but that still only allows pushing patch versions.
If it didn't make the final Winter 13 release, I would have expected Salesforce to take it off the release page. Is this something we have to ask to be enabled?