As of last week have launched our internal private beta of the server-side cookie store. Although cross-site replication isn't working yet, any IDs you synchronize with AppNexus are stored and replicated internally in the cloud using our user cache.

AppNexus ID Service Launched

We are happy to announce that the AppNexus ID service is now live and operational. You can push and pull user ID's by reaching the ID service @ http://id.adnxs.com/id. You can find detailed specifications here: ID Service Standards. Please send any feedback to support@appnexus.com!