MrHard - 4:50 am on May 9, 2010 (gmt 0)
I still believe you can have an authority site and great content and nobody will link. Especially in ecommerce.
Why would they? You can have a peanut butter site and link to jelly, but it's more likely you will just add jelly section of your own. It keeps them on your site longer interacting which is good SEO, and makes it more likely they will buy peanut butter.
I can see some media and article links coming in from good content, but not straight site links.