Audiobooks discussion

Has anyone else checked out Audible.com's new iPhone app? It has so many cool features!
My only gripe is that you can't buy books from within the app... but otherwise, I absolutely LOVE it!
Sorry, I had to share my excitement.
I actually found out about it through this nifty video feature called "Tapped-In"

http://www.youtube.com/watch?v=KOmQAg...

It has promise. But I can't for the life of me found the "sleep" feature that is suppose to be in there some where. They describe it in the help pdf. But no amount of swiping, pinching, flicking etc will get it to show up!