[AlisdairO]

The nice thing here is that it's easy enough to write a mongo compatability layer on top of Postgres (hell, it probably already exists...), allowing you the just-get-to-it ease of mongo combined with the substantially superior engineering of Postgres.

[xdanger]

https://github.com/JerrySievert/mongolike https://github.com/olegp/pg-mongo/ and my favorite: http://pgre.st/