I Can’t Wait for NoSQL to Die: A nice rant against the NoSQL movement. I feel largely the same way. I concede there absolutely are situations where something other than a relational database is the right model, but they are very, very rare.
The idea is that object relational databases like MySQL and PostgreSQL have lapsed their useful lifetimes, and that document-based or schemaless databases are the wave of the future. Never mind of course that MySQL was the perfect solution to everything a few years ago when Ruby on Rails was flashing in the pan. Never mind that real businesses track all of their data in SQL databases that scale just fine. (For Silicon Valley readers, Walmart is a real business, Twitter is not.)
Boring as it might be, RDB technology is highly mature, and is the right choice most of the time.