As previous news articles state, Facebook has some implementation of XMPP going on. XMPP was designed from the ground-up to deal with exactly the issues that he highlights, and is the ideal real-time implementation for any system where everyone is expected to be aware of the statuses of all others on the network (verses the traditional "poll the server every x seconds" methods).
Even if Facebook isn't using XMPP per-say, they have full access to its implementations and source code for internal use for sure.
Granted, Facebook _does_ have the "slight" challenge of having 70 million active users; in light of which near everyone else's IM/XMPP networks are a mere pittance; but the core framework and algorithms are wholly addressed and implemented in XMPP standard.
It's one thing to make a more-efficient implementation of an already-existing standard that scales damn decently verses _designing_ a whole new system to serve their needs.
Note that the article doesn't once mention XMPP though.
Err .. as far as I understood their Jabber/XMPP announcement, these are used for interoperability and integration with 3rd party products only and not for the internal implementation.
So it's only natural that the article doesn't mention XMPP.
Even if Facebook isn't using XMPP per-say, they have full access to its implementations and source code for internal use for sure.
Granted, Facebook _does_ have the "slight" challenge of having 70 million active users; in light of which near everyone else's IM/XMPP networks are a mere pittance; but the core framework and algorithms are wholly addressed and implemented in XMPP standard.
It's one thing to make a more-efficient implementation of an already-existing standard that scales damn decently verses _designing_ a whole new system to serve their needs.
Note that the article doesn't once mention XMPP though.