I think this article makes some good points. In fact there are times when I've been very frustrated at the "We can't to better than RDBMS" attitude many times.

I think this article makes some good points. In fact there are times when I've been very frustrated at the "We can't to better than RDBMS" attitude many times. Particularly that time we were storing a tree in a table. Specialized data stores are very neat. I do however think there will always be a good place for the traditional RDBMS. For instance, there are times when I'm creating that I don't know what the layout of the data will need to be, and where the optimizations will be most needed, so I back an app with Postgres. Should I need to expand later, it will be easier as I have actual data to work with. I guess the point I'm trying to make is: unless you know for sure that your data will benefit from a different model (e.g. known performance needs, or a better conceptual mapping), not using an RDBMS seems like a premature optimizaton.