Cassandra 2.0 requires Java 7 (See [here](http://www.datastax.com/dev/blog/whats-under-the-hood-in-cassandra-2-0)) which is only available from Oracle. (Apple only offers Java 6.) It may well be possible to get by with just the Java 7 runtime, but at least with the default installations, Cassandra and Java 7 RE cannot find each other. The default installation of Java 7 JDK, however, works fine with the default installation of Cassandra. Since my objective was to avoid messing around "under the hood" and instead use simple, default installations whenever possible, the recommendation is to go with the JDK rather than the RE.

I wanted to add an extra caution about Cassandra 2.0 here because that's the default Homebrew version and one has to take extra steps to install 1.2 instead.