Instant chats and central servers

[Sean Donelan <sean () donelan com>]

A question (and a test to see if I'm still subscribed)

The various instant messenging services, such as AIM, ICQ, Microsoft,
Yahoo, other Messenger uses a central server to manage "presence".

No central server appears to mean no instant messages, am I correct?

What does this have to do with NANOG, apparently it is becoming more
common for backbone NOC folks to communicate with their friends in
other NOCs via one of these instant chat programs.  I didn't realize
how common it was until I was informed about it last month when AOL/AIM
had difficulties.  This month Yahoo Messenger had power difficulties,
which disrupted their central servers.

If folks are using this these services for real-time communications,
should we be trying to improve their reliability?  Or is this just a
"feature" of how presence services work.