Mr. Kanarek is definately all over the web talking up Pentax digital gear, and as I understand from his posts elsewhere Pentax is loaning him the gear to use. It is my opinion, due to the proliferation of similar posts, that he has some sort of agreement with Pentax to spend time on popular photography websites/forums posting about Pentax gear.
On the other hand, he does appear to be using the equipment for his pro photo jobs, and relating his experiences. As long as these are real jobs, not set up by Pentax, and the information/opinions are honest, then I think his posts are valuable. Just like anybody, you can google his name, read up on what you find, and decide for yourself.
Many photo magazines and bigger gear websites are straight up funded by Canon, Nikon, etc..., and post articles and reviews written by the camera manufacturers themselves, although they are usually presented as being independent. Canon and Nikon provide loaner gear to dozens, if not hundreds of pros to get more visibility. When I worked at a camera store Nikon and Canon (and other brands) paid bonuses to salespeople for selling (pushing) their gear; the salesperson got a lot more money for selling a Nikon/Canon SLR with a Nikon/Canon lens, than if they sold it with a cheaper Tamron or Sigma lens (remember that as the salesperson explains to you the magical properties that make Canon and Nikon brand gear superior to other established brands/manufacturers). The Nikon rep was one of the sleaziest bastards I've ever met.
At the worst, Benjamin is showing us that brand name really doesn't matter, and anyone competent should be able to get decent results from whatever gear they are using.