I have the same issue. The force update trick using the back button doesn't seem to work. After looking at the version numbers on a couple different apps, its only showing NoDo apps. Maybe the market won't get updated until your carrier starts rolling out the update. I hope its just a bug tho. I'm on AT&T and had to force my update to get this mango goodness rolling, but no mango apps to try out. Lol.
I noticed eBay have two versions in the marketplace - one NoDo and 1 Mango. No idea why they didn't just update but I uninstalled the old one and installed the Mango one and now have the scanner and new layout.