If you're thinking of connecting AIR app on PC 1 to AIR app
on PC 2, you can't do it directly because AIR applications don't
support listening sockets (that is, they can't be server apps).
But you could have some server app running on pc 2 and the
air app on the pc 2 could be a client to that server app. AIR app
on pc 1 connects to the server app on pc 2, air app on pc 2 gets to
know about this from the server app.
Or better yet, you could have a central server to which all
the AIR apps are connected to.