Whether we quibble about the meaning of "competition" or viable alternative products, the fact remains that AD is a huge powerhouse in the enterprise. Ignoring it doesn't help. Criticizing it (valid or otherwise) doesn't help. It is there because IT managers are buying it, and they're going to keep on buying it.
Right now, the one single thing that keeps me from using Linux on my desktop is authentication against the corporate directory. If we can bridge that gap, it only opens doors.
I'm very much looking forward to the next part of this article.