I may no longer play on the server I started out on very often as of the moment, but I am very glad that Blizzard came out with Real World ID so I am able to keep up with my friends from Runetotem. I believe that most of my friends are now playing on different servers as well and on Horde and Alliance sides.
Even through all the different changes with servers and sides, one thing that still remains consistent is that we are able to talk about anything still. Complaints about groups, family life, other friends, even the pets. It is whatever is on the mind at the time.
I believe I am lucky though. I have at least one friend on each time I log in.
Some I talk to all the time and others I hardly talk to but we are able to pick up a conversation easily.
If I were to ever stop playing, I would more then likely try to get all the email addresses of everyone to be able to keep in touch. I would hate to lose touch with any of them.