In an interview with Gamasutra (via Siliconera) Eidos Montreal General Manager, Stephane D'Austous revealed the key to the studio and their corporate owners harmonious relationship: autonomy.
“The honest truth of that is they realize that by taking us under their wing, they knew that we were doing a lot of good stuff, so they fully respected [that]. It’s a partnership, more than a father and a son kind of relationship, so they let us really do our stuff. They don’t intervene at a micro level, and I report directly to Phil Rogers, who’s the CEO of Square Enix Europe.”
It's fortunate and wonderful when a AAA studio is successful in establishing a relationship like this with their owner. Even more so when it bears fruit like Deus Ex: Human Revolution, which is by most accounts, one of the very best games of last year.
D'Astous was also asked about the necessity of Square assembling their Square Enix Montreal studio. He revealed that while EM is growing, corporate wants to cap that team at 450 people (so don't expect an EM project boasting Assassin's Creed numbers.)
Eidos Montreal's current focus is Thief 4. It should go without saying, but I can't wait.