For what it's worth, a pristine checkout of Eucalyptus[1], that has parts written in Java, appears to be around 430k loc of java (comments and white space included).
Also, OT, didn't realize Eucalyptus had worked so much towards friendly development, and was moving towards including RiakCS as a S3 work-a-like backend[2].
What I've heard from a friend who's a SDE there is that because they have a Service-Oriented Architecture the individual teams can use just about whatever language they feel is best for the particular job. The other teams don't care because they're just making service calls. I'm sure that was mostly Perl in the 90s, but today it is mostly Java, because their HR strategy is basically to hoover up all the fresh CS grads, whose strongest language is almost always Java. And also because when Amazon started building their SOA, Java/XML/SOAP was all the rage.