<p>Can pipes be used across LAN computers?</p>

<p>In particular I'm looking for Windows, but if you have more info on other platforms, that will also help others who find this thread later. </p>

Yes they can.
Named pipes can be used to provide
  communication between processes on the
  same computer or between processes on
  different computers across a network.
  If the server service is running, all
  named pipes are accessible remotely
http://msdn.microsoft.com/en-us/library/aa365590.aspx