On the first day Homecoming was listed, I reached the top 8% in terms of sales ranking after selling just five books.
In a sense, this isn't surprising. We know that most self-published books, even in these days of easy and inexpensive self-publishing, don't make money. We also know that most people who write books and put them out there haven't given much thought to marketing and don't really know how to promote their books (or don't have the time to invest). And finally, not every book is going to sell copies through this one outlet every day.
This cuts both ways for those considering self-publishing to Kindle. On the one hand, it appears that you're not really in competition with 478,000 other books--at least, not if you plan to do some strategic promotion of your book rather than simply relying on browsers finding it in the Kindle store. On the other, it means that the vast majority of books--particularly fiction books that fall into broad genres like Romance or SciFi--will never be seen by the typical shopper. Even the edge that should go to new publications is lost because sorting by publication date yields several pages of not-yet-released books...so even if your book was published two minutes ago, it's likely to be several pages deep in the listings.
It's early in the game, and I will be doing quite a bit more monitoring and playing with different variables, promotions, etc., but thus far my conclusion is very similar to the one I offered about self-publishing in hard copy back in 2008: it can be successful if you have a niche topic that people are searching for, if your audience is concentrated, if your name or brand is already known or if you have the time and skills (and possibly cash) necessary to conduct your own marketing campaign. If not, only one element of the analysis has changed: if you use a system like Kindle Direct Publishing, it won't cost you anything to test it out.