Note that it's not 1000 servers every week, it's up to 1000 servers in a given week. This was likely done to support the launch of a new game, and may factor in server turnover (they're on EC2).
That being said, launching 1000 nodes for non-batch jobs is still pretty remarkable.
Zynga can have absolutely crazy growth on launch. FarmVille was growing few million users a week.
Also keep in mind interactive multiplayer games with persistent state are different beasts compared to usual web applications. Games are very write heavy and do not cache well.
That being said, launching 1000 nodes for non-batch jobs is still pretty remarkable.