Some people use the terms Print-on-Demand (POD) interchangeably with Self-Publishing. However, not all self-publishing is via POD and vice versa. I think a more distinct differentiation needs to be made between self-publishing POD and being published by a publisher who uses POD.
While it is an uphill battle getting your self-published POD into stores, it is a completely different scenario when a reputable publisher backs you and uses POD. Many small publishers use POD as a way to economically access the print version market. There is no way many of these small publishers could afford to invest in a run of a few thousand paper books. POD is the only way they can compete. Good small publishers will make those POD books available through Amazon.com and distributors (like Baker & Taylor). The POD publisher covers all set-up costs involved with the print edition of the book. Since the book is only printed when someone orders it, POD is an environmentally-friendly technology - and writers can tout that when they are trying to get their books reviewed/featured in magazines.
Publishers who choose to use POD as their print platform also normally supply the cover artwork, as well as editing and galleys, at no charge. Many of these publishers primarily feature e-books, and they also cover the set-up fees associated with companies like BookSurge. These are real publishers.
So, there is a huge difference between self-publishing with POD and going with a real and reputable publisher who uses POD to make your books available to those who want to hold a copy in their hands.