Hello all,
the Hibernate Search team has many years of experience integrating Hibernate ORM (JPA) applications with Apache Lucene, and we're now working to make this popular engine to integrate with Elasticsearch, as an alternative to embedding Apache Lucene.
We just released our 3rd Alpha release today:
The previous post contains some more practical examples to get started:
You're also welcome to watch the "Elasticsearch" tag on the Hibernate blog:
There's still much to do, but it starts to be quite useful already so don't be shy in trying it out.. we love feedback and early adopters have a chance to make great impact!
Also, if you're looking for a new OSS project to help this is a great time to join the effort 
-- Sanne