Cloudata is a new open source implementation of Google's BigTable paper. It can be found on Github here. It appears to be the project of a Korean developer named YKKwon.

As noted at MyNoSQL, there are only a couple commits and it's not clear how serious this project is. But it will be of interest to big data, MapReduce and BigTable buffs.

Summary

The need to look at Non SQL systems arises out of scalability issues with relational databases, which are a function of the fact that relational databases were not designed to be distributed (which is key to write scalability), and could thus afford to provide abstractions like ACID transactions and a rich high-level query model.
All NoSQL databases try and address the scalability issue in many ways – by being distributed, by providing a simpler data / query model, by relaxing consistency requirements, etc. I find it useful to bucket them as follows:

Distributed vs. Not-distributed: Distributed databases take the responsibility of data partitioning (for scalability) and replication (for availability) and do not leave that to the client.

Beware! the article is quite long.