Now on Marketplace for all Xbox Live members except those in Asia.
Edit: I am getting reports that some folks can't see this or the UMKIII arcade title. I have escalated to the operations center. Until then…no need to post that you don't see it. It's been a helluva week, huh? Edit: Both MK and TH are starting to appear in Marketplace for folks…if you don't see it yet, give it time as the team is actively working on this…meaning it may appear/dissapear/re-appear. Both titles will be available as soon as they can address the issue. Again, thanks for your patience. I won't have a chance to check for an update for a few hours, but it should be fixed by then. By the way: Your abilty to see (or not see) the content has nothing to do with your geo-location.
Edit: Ok, looks like the ops team has fixed it and everything is now in order with this and the Arcade title.