We couldn't be more please, as it's a great next step for Facebook to capitalize on all the "eyeballs" that are latched onto Facebook.
For those unfamiliar with the new offering, Facebook has moved the "messenger" icon from the bottom center of the main UI to the top left -- just to the left of the search bar. In it's place is a new "shop" icon which links you to items listed by Facebook users close to you.
Listing items is easy -- just provide a title, picture, category and some text.
This is definitely an early version of what's to come. First of all, no payments can be made on Facebook. So buyer and seller must transact in person. That means a traditional "sell and ship" e-commerce model is not yet supported. We expect that to change in subsequent iterations as it's simply too juicy of a revenue model for Facebook to ignore.
But, again, it's early -- watch for updates in the next year as Facebook builds out an understanding of what makes most sense to do next!