OK, I have been looking at this thread of discussions and at the risk of offending some people, I felt inclined to say something objective here.
First and foremost, O'Reilly Network have been offering a lot of content for free and readers have been enjoying this benefit for a long time. Ask youself, have you been asked to pay a single cent for the O'Reilly Network content?
And in this particular instance, what O'Reilly has done is advertise that an PDF book is for sale (which happens to be mine). If you don't like it, just ignore it and move to the next article that is free. What a lot of readers do not understand is that publishers do need revenues to survive. The next time you see an advertisement on TV, please remember to write in to complain that "that is just pure spam".
I am sorry this comment of mine has nothing to do with ClickOnce and that I have wasted your valuable time reading it.