This is getting interesting. It's not just that Amazon and B&N are competing to see which can sign more retailers, thought that is fun to watch. No, I was thinking of one of B&N's early partners, Books-A-Million. At the time they decided to carry the Nook it was a big deal. Now they're just one of many retailers, and they lost all this time they could have been building their own identity as an ebookstore.
At this point i think they should sign up with Kobo, and maybe even buy Border's stake. BAM! have been left behind in this niche.