The other day I wrote about the New York subway (my favorite impromptu research panel), and a few “hang outs”, still more comfortable reading a real book rather than their e-version.

Of course, despite some anachronistic readership, the world of e-books continues its expansion undeterred. 

The latest: Online retail giant Amazon.com announced, the library of books available for it’s Kindle branded e-reader will now also be available on Apple’s iPhone and iPod Touch.

Why is this big? 

If you hear yourself or anyone else equipped with either Apple-branded portable, we’ve all started asking what’s on it, as if asking what’s on television or on the radio.

Couple that with the by-now impressive depth and breadth of repertoire available for either device, Apple portables are anything but shy compared to, yet again, television or radio.

In other words, the iPhone / iPod combination of devices has become a media platform in its own right.

For Amazon to jump on board makes perfect sense.

More on the subject:

Amazon’s Apple Deal: Kindle Cannibal? (Business Week)

Amazon releases Kindle for iPhone, iPod Touch (LA Times)

Amazon launches Kindle application for the iPhone (TechCrunch / Washington Post)

First Look video: Kindle for iPhone (cnet)