Mozilla has been demoing its Firefox OS (née Boot to Gecko) since Mobile World Congress earlier this year (and developers have had access to it since this summer), but there are still a lot of unknowns with regards to how the final product will look when it arrives in 2013. One question appears to have been answered today, as Engadget has obtained what it says are images of a fairly complete version of the Firefox OS Marketplace. As expected, the Marketplace will be where users go to download new apps for their Firefox OS devices, which are due to first arrive from Telefonica, with other carriers to follow. The images show typical app store features: there is a search bar, categories, ratings, and details for each app, but not much else. Curiously, there appears to be only free apps available in this version of the Marketplace, so Mozilla still may be hammering out its payment methods for purchasing paid apps through the store. Either way, we expect to see more of Firefox OS revealed as we get closer to its 2013 launch.