That article you linked to is one of the craziest things I've ever read. RDBMSs are powerful enough to do anything -- but so many engineers are too lazy to learn proper SQL.
If you need to handle more transactions or queries, buy a bigger box. You can have hundreds of TB in a nice enterprise-grade server. If you HAVE to run your data across multiple machines, just spend some time and actually *think* about what data you want where, and then write a little code to send it to the right database.
Even Google used a ton of MySQL boxes for a long time to deliver their searches. Scale-out architecture is a lot more of a lie than its proponents make it out to be, check out this post on CodingHorror.
Eventually, all these new "databases" will need to actually be used in a *real* environment, and they'll have transactions, SQL support, indexing, a good UI, and everything else. All MS or Oracle need to do is a little tweaking to make their multi-box configurations more robust, and they'll crush everything else.