I've read some very, very good self-published books that seem to be having difficulty getting noticed above the background of so many other self-published books, even after having done all of the "self-marketing" things recommended by advocates of self-publishing, and I think this is a symptom of over-saturation in self-publishing. There are simply too many books available and no way for the reader to sieve through the mass to find the best. There is no mechanism to take the place of the big pub editor as an indication of a level of professionalism and base-line quality. I've heard arguments that it should be left to the readers: if your book's any good, the readers will find it and buy it. At this point, I think we can all agree that this isn't necessarily true.
I hope the self-publishing model comes up with a medium between the free-for-all of current self-publishing and the eye-of-the-needle model that big publishing represented for a hundred years.