I've written something similar for PostgreSQL using Paxos: https://github.com/citusdata/pg_paxos . It can replicate tables across a set of PostgreSQL servers.

pg_paxos is an extension that uses PostgreSQL's query execution hooks so it doesn't require any external components. An advantage of pg_paxos is that you can do reads and writes on any node. Would love to know what people think and whether it's something you would use (if rigorously tested). Small warning: it replicates SQL queries and doesn't stop you from using volatile functions like now() yet, which would give inconsistent results.

A possible application is a reliable cron service. Each cron node tries to add an entry to a replicated locks table with the same primary key on any of the PostgreSQL nodes. Only one will succeed and then runs the cron job.

Some more details in these slides: http://www.p2d2.cz/files/pg_paxos.pdf