I doubt such companies would put their data "in the cloud".

And if they don't, the cost of supporting this "straightforward" Hadoop infrastructure, both in terms of hardware, engineering and support, is so massive that the little elbow grease for a simple I-know-what-it-does solution may well be worth it.

In other words, I share alexro's concerns. If you're buying into the M/R hype and process your blog logs in the cloud, that's one thing. But legitimate business use-cases are probably not as common as people may expect/hope.