Multiple databases, in multiple geographic locations while preserving PostgreSQL triggers and data consistency
Streaming replication fires the triggers on the master only.  The slaves never see the actual table writes, but rather re-run the recovery logs from the master.  Because this is essentially a recovery situation, it means that the binary tables are guaranteed to be brought up to a consistent level.  No triggers are necessary.  Triggers may be possible with Slony or Bucardo but I am not 100% sure.  My initial thought suggests these should allow triggers in downstream databases but you don;t want to run the same triggers on both databases!

In current releases you can't cascading replication outside of Slony.  In 9.2 streaming replication will allow for cascading.

Hope this helps.