Yeah, I realised after typing it that there's probably a huge amount of availability bias in my statement. It wouldn't surprise me if Wordpress MySQL deploys outnumber all rails/django postgres deploys combined. And the PHP mainstream isn't moving away anytime soon.

MongoDB, though - I do question that, however I have no figures and it again probably depends on the circles in which you move whether you see a lot of it or not. I don't move in node circles much, so I hardly see it at all.

Mea culpa. That said, in the startup-filled tech incubator in which I work, and in which rails is pretty dominant, postgres is king. Make of that what you will.