As announced here, I put a Debian package together for Cassandra 0.3.0.
I don't have any (immediate )plans to upload a Cassandra package to the Debian archive, (this package isn't even policy compliant), so consider this unofficial and report any packaging bugs directly to me.
deb http://people.apache.org/~eevans/debian cassandra/ deb-src http://people.apache.org/~eevans/debian cassandra/
The Apache Cassandra team has managed the release of 0.3.0, its very first.
It took a lot longer than I had hoped to get a release in the can, (almost a month from the approval of the last release candidate). Part of this was a lack of familiarity with ASF's processes, but part of it was poor or incomplete documentation, or lack of consensus about what is required. In the end, it boiled down to a combination of carefully studying what other poddlings had done, and a few iterations of trial-and-error.
I'm confident that this will all go much smoother for 0.4.0, (which is progressing nicely, and should be ready Real Soon Now).