Baruwa is capable of running in a distributed setup, It uses REST to process quarantined messages residing on other nodes, the only requirement is that the nodes share session infomation. If you are running your nodes from the same database backend or running multi master replication then this will work out of the box.
The baruwa implementation differs from the mailwatch one in that it uses REST and the users credentials to process the message on the other node, mailwatch uses an XML-RPC system which does not use authentication.