Any dealings are probably Bethesda-level, given that Zenimax has a subsidiary making TESO as a PC exclusive and badmouthing the 360's hardware capabilities, which is hilarious because the very last thing PC gamers want is another self-professed WoW clone. So console owners are jealous about TESO and some are even buying PCs for it even though the PC market at large has very low hopes for the game after finding out it used Hero Engine and had "similar to WoW gameplay." Somehow they've actually managed to rustle the feathers of two sectors of TES fans at once. Still, I think it shows that Zenimax has no MS agreement. If they did they would have their subsidiary cut down the MMO's scope, gameplay, and visual quality until an Xbox 360 could run it, and the devs certainly wouldn't be insinuating that their game was too high quality for a console release (more or less what they said regarding PC exclusivity).
This is essentially the crux of the problem. The console is out of date and in dire need of a new release. The problem being that the poor manufacturing process of the XBox 360 has led to so many recalls that over a billion dollars has had to be recouped. And it is being recouped by extending the life of the 360 well beyond where it should be. It's a lose lose situation for the consumer (both PC and console) who are, in effect, being held back. The increasingly diplomatic language being used by developers regarding the 360 hints at what games companies actually think of the situation, but it's a great shame that Microsoft wield so much power that they are capable of stalling an entire industry. Still, the new consoles should be here next year so the situation will be back full circle and the new cycle can begin.