On CloudDB: Why I didn't list it separately
A couple of CloudDB developers/fans have Tweeted that I should have listed CloudDB on its own merits, but there are several reasons why I didn't. First off, Cloudant is the only support option we know of for CouchDB (Are we missing a real option, here? We've asked and searched to no avail.) Cloudant only offers it as a service in the cloud. Second, there's evidence that CouchDB has been "eclipsed," as I state in my commentary on Cloudant, by rivals including Couchbase and MongoDB.
If CouchDB were more in demand, wouldn't we know about a company staking its future on supporting CouchDB on premises? I'm not disputing that CouchDB was early to NoSQL and has many fans. But without support, there is no hope for CouchDB to see broad enterprise adoption. If not for the existance of DataStax, for example, I would not have listed Cassandra. And if not for MongoDB the company (formerly 10Gen), MongoDB would not be where it is today.
In the case of CouchDB, it was included indirectly only because IBM bought Cloudant. IBM has the wherewithall to do whatever it wants. If it wants to support CouchDB on premises, the fortunes of CouchDB, the open source database, will greatly rise. Rivals speculate that it only bought Cloudant for its database-as-a-service technology. That's why CouchDB - by way of IBM/Cloudant - is a NoSQL option to watch. We'll find out soon enough whether IBM is going to throw some real weight behind CouchDB.