This post is being linked everywhere, it seems.
Let’s take Zack’s arguments one at a time, beginning with the most egregious first.
His “hosting cost” argument is total nonsense. Assuming that you even want to do your own hosting and delivery (rather than just letting Amazon, B&N, et al do it for you), you can get 20 gigs of disk space and 200 gigs of bandwidth for $19.95/month. That’s enough to hold roughly 10,000 different books and deliver 100,000 copies per month (assuming 2 MB per book; obviously that’s going to be different if the book has (e.g.) many large color images, but even in that case it’s still going to be a trivial expense).
You don’t need to pay “third-party hosts with experience in ecommerce” “four- or five-figure set-up fees” to put your book in the Kindle or B&N stores. You can do it yourself in about 15 minutes. For free.
You do still need copy editors, cover artists, and so on (assuming you can’t do those things yourself). What you don’t need to do is hand over the lion’s share of your revenue to some middleman in (effective) perpetuity in order to get them. There are people who will edit your book and create a cover image for a flat fee up front (in fact, some of them are the same people who do those things for the “professional publishers” — those functions are largely outsourced anyway). You don’t need to pay an agent 15%, either.
Later, in the comments, he trots out the tired old “without professional editors we’ll be buried under a mountain of crap” canard. Yes, there is a lot of self-published crap. There’s also a lot of professionally-published crap (cough…Snooki…cough). So what if it’s mostly crap? The web itself is the largest slushpile in the history of the human race, yet somehow I still find more good stuff than I have time to read.