Elgg interconnect

I have this idea: Can you imagine that there was the possibility of interconnecting all the Elgg facilities creating a big decentralized social network? Pro example:

A user is logged on an installation of Elgg and get some cookies with your data later accesses another Elgg installation and the installation detects cookies and you create a user account automatically.

A user posts a post in Elgg installation and the installation pings to other facilities Elgg where the user is registered.

They are quick examples, I think we could do much more :)

What do you think?