The idea of this feature will be that servers are able to send a packet to a client witch tells the client to connect to another server (The IP Address should be send with the packet). This feature gives (for example) Bukkit servers the ability to let players teleport to other servers, if the community has a second mini game server for example.
Safety / Public Key
The only problem this feature will have is that servers are able to teleport players to servers they are not allowed to. The idea is that each server should have a 'Public Key' in the server.properties file. If the packet was send to the client, the Public Key of the other server should also be send with it. This is needed to be able to connect to the other server (or maybe optional). Using this idea servers aren't able to connect to other servers unless they have the public key.