What Does Out of Print Mean in a POD Era?

A contract language change by Simon & Schuster that makes all its books available by print-on-demand technology "in print" has raised the hackles of the Authors Guild. The issue is that as long as a book is in print the rights do not revert back to the author, who could then look for another publisher who would actively promote the book and boost sales.

Source: Rich, Motoko. "Publisher and Authors Parse a Term: Out of Print." The New York Times, 18 May 2007, C3.