Amazon announced today that it is acquiring Audible.com, the best known digital audiobook company around. The resources of Amazon behind Audible? That’s great news for consumers. And for Amazon itself, what a way to build up digital content. As Brad Linder over on Download Squad points out, we’re seeing an Apple vs. Amazon arms race. With Audible.com and its growing selection of DRM-free music, Amazon is certainly building an impressive stockpile.