I'm doing this with a class I'm teaching, but I think it works better for small research/discussion-oriented seminars than larger introductory courses, where recent papers are most relevant. For intro courses, coming up with good intro materials is a fairly hard problem. If I were teaching an intro course on theory of computation, for example, I would probably still use Michael Sipser's Theory of Computation, because it's good, and I don't think I would be likely able to put together an equally good replacement out of freely available materials. I would, though, try to make sure that the course didn't prevent students from using the previous edition (which is now available cheaply).