Data Startup Acunu Opens The Castle Gates brings to light a start up that's building a new storage platform, focused primarily on Cassandra at this time. They've recently open sourced their platform and they're looking for people to start working with it. http://www.acunu.com/2011/05/open-castle/#more-1930.
If you're working with Cassandra, this looks like it's really worth checking out. http://www.acunu.com/product/benefits/.
It looks like you need to sign up for the beta program to try it. http://www.acunu.com/product/beta/
http://www.acunu.com/docs/html/installation.html has the instructions to install. There are a variety of options including a USB stick image, or VM images for a variety of popular platforms including ZenServer, KVM, VirtualBox, and VMWare Fusion.