Funny you should mention product placement in novels, Bron. I thought my upcoming release, Lights! Camera! Fiction: A Movie Lovers Guide to Writing a Novel, was a logical match for a movie rental company such as Blockbuster or NetFlix since the assignment for each 'lesson' in the book is watching a movie. Wrong. I was told (snottily by one of them) that they did not "do cross promotions with books."
So I became an affiliate.
And here's a little shameless promo: Want to help prove that product placement or cross-promotion with books is a great idea? Go here: http://www.lightscamerafiction.com/links.html
Get a month of Netflix free. On me. Try it. If you rent three or more movies a month, you'll love NetFlix.
Who knows, maybe diamonds and chocolate will be next if companies see the value of a little cross promotion.