Rough Java Implementation of GCD

Produced a rough Java implementation of Grand Central Dispatch APIs -- at this point, only the "classic" API forms, not the ones that rely on code block (or "closure") concept. JDK 6 doesn't support closures.

Lots of Tests with Casssandra

I have been doing some tests comparing the speed of EC2 "local" file manipulation vs. speed of EC2 EBS volume file manipulation. The difference is significant. I have also been doing lots of tests with Cassandra, including some with Cassandra deployed on EC2 and on EC2 with EBS, all at AWS. Interesting results. Cassandra delivers most everything it promises as far as replication, partitioning and recovery are concerned. Pluggability of partitioning and replica placement strategies are a definite plus. It would be good to have some more pluggability in data file format and composition. This will be harder but worthwhile to accomplish.