He recently posted an article talking about Agile Development and Usability which, like I said, I mostly agree with. Really the only part I cringed at was where he says:
"It's perfectly feasible for developers to do interaction design and usability."
Now, I have no problem with developers being involved with usability testing. I think it is extremely valuable to for them to see first hand how users act. The part that bothers me is that it is next to impossible for developers to have an unbiased opinion when analyzing the results of user testing. In my experience, it is because developers know the ins and outs of the system too well to appreciate the way users perceive the system. A designer on the other hand is in a better position to be looking at the system the way an actual user would.
Like I said, I mostly agree. His suggestion for usability and design to happen in a parallel track is one that I have advocated for a long time and has been very successful for me. His suggestion that Foundational User Research should occur before a development project even exists is spot on. This work and much of the work done by interaction and experience designers is just as much a part of the product strategy process as it is the development/ implementation process. So, part of it must be done during the strategy phase long before developers start writing code.