I wrote a fairly detailed post about the Death of the Swiss-Army RDBMS on my blog, http://www.roadtofailure.com :)

The RDBMS has been used for way too long as a generic "bucket" for any sort of data storage and analytics. As a result, speed and scalability have suffered. With Social Media and the advent of "web-scale" data, engineers need to realize that the storage and analysis solutions they use must be driven by the type of data they're storing, and what they want to do with it.

As I stat, "The ACIDy, Transactional, RDBMS doesn’t scale, and it needs to be relegated to the proper dustbin before it does any more damage to engineers trying to write scalable software."