Interesting that one of the original "noSQL" databases that is still going strong today, Pick and its variants, was not mentioned in the article at all.
Universe and JBase are both well supported on Linux and there are several multi-billion dollar (revenue) companies running their core business on it - I work for one of them.
Both UniVerse and UniData are equally well supported on Windows, Unix and Linux. They have some interesting features that are still reasonably unique in the database world. E.g. Built-in transparent record encryption, including both key & index.
http://2012.nosql-matters.org/cgn/wp-content/uploads/2012/06...
Full disclosure: I'm the product manager for the databases.
You're probably familiar with the Eclipse distribution management package then (not to be confused with the IDE), that's the app I was referring to. I've been using Universe since the Vmark days, ADDS Mentor and Sequoia before that. Pick type databases are sadly under-rated. Possibly because there's never really been any kind of marketing aimed at indy developers and/or students?
Universe and JBase are both well supported on Linux and there are several multi-billion dollar (revenue) companies running their core business on it - I work for one of them.