Postgres Clustering

I've got 2 pc with postgres 7.2.4 on. First server is where i want to work, and 2nd server is where i want a lan mirroring.
Now i'm using heartbeat and rsync but this work correctly only when postgres is stopped on each server.

How can i do a lan mirroring between my server! I know that with mysql is possible but with postgresql?

thanks @wdani