First of all: I love the idea... selling streight from your inventory.
However: The only difference I see so far is, that instead of sending the items to the MP site and managing the listings there you now manage your folders in your Viewer. But the management of the listings still takes place on the website. So how exactly is this viewer-Managed Marketplace?
I mean if it is viewer-Managed I would presume that you can handle everything in the viewer. Sort of like the Preferences settings of objects in your usual inventory. only here you would see the entire list from Title over description, prices, keywords....
Right now it looks like the same thing but instead of actually sending it is sits in a folder in your inventory. And you can switch out objects in folders a little easier.