There is something fishy here. Neither www.corporate-ir.net nor corporate-ir.net resolve. And the site asks you to login.

Relevant link is:

http://www.amazon.com/exec/obidos/tg/browse/-/465600/

A whois query (http://who.godaddy.com/whois.aspx?domain=corporate-ir.net...) reveal corporate-ir.net domain belongs to Thomson Reuters Holdings Inc.

I got this link from https://twitter.com/amazoncareers. Now, that account is authentic or not that's another question.

FWIW, if you go to http://www.amazon.com/pr (which I think you can safely expect to be owned and operated by Amazon), you DO get redirected to corporate-ir.net. That's what ultimately convinced me that the press release was legit.

It still bothers me, though.

You can also find the same information about textbook rentals by going directly to Amazon's site and going to their textbooks department.