Barring this we (place where I work, Chango) will probably eventually fork Cassandra to have a RESTful interface and use the Jetty async HTTP client to connect to it. It's just ridiculous for us to have threads and associated resources tied up on I/O-blocked operations.

We've done exactly this but with Netty rather than Jetty. Helps too because we can easily have testers look at what we put into our CFs. Took some cheating to marshall the raw binaries into JSON but I'm pretty happy with what it's bought us so far. 

Are you capable/willing/interested in sharing the work you did? 

Ryan