PSP vs. iPod vs. DS, or what?

Striegs writes in his two cents on the whole PSP vs. iPod thing:

Okay, I don't know what to make of this anymore. The rumor in question is that Sony will offer an iTunes-esque music and video download service for the PSP later this year. At first, several articles reported it to be a miscommunication, and Sony themselves denied it. But now I happen across several articles that state it as irrefutable fact. Who's to say who's right? Actually, I don't think it really matters. It's a good idea, one that Sony would be stupid not to capitalize on.

However, here's the thing that really (REALLY) intrigues me. In almost every PSP-related article I've read, Sony makes remarks such as, "we invented the portable music market, and we intend to get it back," or, "the iPod is simply a fad,"
or the inevitable, "the PSP is the Walkman of the 21st century." In these same articles, Sony often fails to mention anything at all about the PSP's gaming functionality. The more I look at it, the PSP seems less and less like a shot at Nintendo and more and more like an attempt at Apple's market share.

So here are my questions: is the PSP nothing more than a Sony Network Walkman associated with the PlayStation brand?
Who is it intended to overthrow, Apple or Nintendo? And, if faced with the dilemma of supporting one or the other, will Sony abandon the PSP's gaming abilities just to reclaim the portable music market?