PosgtresSQL master-slave synchronous replication to multiple slaves

PostgresSQL has support for master-slave replication, but the synchronous streaming replication only supports a single synchronous slaves. You can have multiple slaves, but only one will be synchronously updated the others being eventually consistent.

Synchronous replication offers the ability to confirm that all changes made by a transaction have been transferred to one synchronous standby server. This extends the standard level of durability offered by a transaction commit. This level of protection is referred to as 2-safe replication in computer science theory.

If you run a large enterprise system in a master-slave replication scheme on top of PostgreSQL, what options do I have for enabling multiple synchronous slaves? Has anyone been able to set-up such replication configuration? Original SQL question:

http://stackoverflow.com/questions/23954844/posgtressql-master-slave-synchronous-replication-to-multiple-slaves