lucene / hibernate search in cluster

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We are using hibernate search that is an abstraction on top of lucene.  Has
anyone used this in a clustered environment?  There is built-in JMS ( master
/ slave ) support for this but the assumption is that the slaves get updates
every 30 minutes or more from the master.  Our application requires that all
indexes be up to date within ~5 seconds after metadata changes.  Our index
is not huge, < 500k rows and the amount of index on disk is currently only a
few hundred megs.