As someone who unhooked from the ever-online world of BB to an iPod Touch and realized that I didn't need to be that connected, I think Kindle's whispernet is nice, but not a killer app. Gimme WiFi and we're cool.
With that as a premise, check out the new Sony Reader and Reader Touch ($200 and $300 this fall). With 1 million free books, the ability to read office docs (for FREE mind you), and Sony's tight hardware design, I don't know that its worth waiting around for Kindle or its DX big sister. Seriously.