Public Peers, aka "Pubs"
To sync across the Internet, "Pub" nodes run at public IPs and follow users. They are essentially mail-bots which improve uptime and availability.
The Scuttlebot community runs some Pubs, and anybody can create and introduce their own.
Tokens which may be used to command specific Pub servers to follow a user. These are used to join Pubs.
an essential part of the idea with pubs was to use them as introducers like this. needing a signalling server for introductions seems centralizing, but if that service is generic and people have a reason for running them (as pubs have already demonstrated - already more people than we expected have decided to run pubs) then that service becomes decentralized.