What Makes It NoSQL?

An interesting post on the NOSQL Group about what takes a storage to be considered NoSQL:

1. SQL-the-language vs. alternate query languages
2. A tabular model for data as opposed to one that is not (e.g. key-value, object, graph, …)
3. ACID vs. non-ACID
4. Centralized vs. distributed/decentralized

In case we agree with the author, Johannes Ernst, then we might be tempted to conclude as he does:

It’s interesting to observe that any “NoSQL” product could be “NoSQL” in any number of these dimensions. […]

Which would also explain why so many “NoSQL” products are so dissimilar to each other.

So, what makes it NoSQL?