howto: 2 users interactively edit the same file ?

[Matt Carlson]

Hi all,
  I'm trying to figure out how to accomplish the following: My friend 
and I need to work with the same file at the same time.  It would be 
nice to be able to code simultaneously and see each others changes
in something like real time.  I've googled everywhere and found only
information on how emacs handles locks.. I'd like both he and I to 
be able to edit the same file and see each others changes as close to 
instantaneously as possible.

  The sky is the limit with emacs, so I'm sure there's a way to do this, 
I'm just in need of some direction as to how to do it, or even what 
words to google.

  It would be very nice to have a shell open in one buffer to chat 
with the other person editing the file, and then the file we're both
editing open in another.. Thanks in advance, 

-regards, 
Matt