The "shut it down, you lose all your stuff, and we're starting over" strategy worked for Amazon and ereaders (result: Kindle), but hasn't so much for Microsoft and music (result: Zune marketplace).
I think I remember getting a few "promotional" ebooks from them before. Interestingly, if I go to my "account" page and look for "Your Media Library," one of those links takes me to all of those. So, if you are referring to that effort, you can still get to them. I don't know why they did not unify these with the kindle.