Exceptions exist everywhere, the game industry not being an exception o.O. Really, the smaller the company the more interactive everything is. But when you get into much larger companies with like 100-200 devs, and even multiple development houses under a single publisher, the more focused everyones job is.I just want to chime in here real fast on the Lord Alchemy and Dragontamer discussion about design...
I work in game development and the roles and responsibilities that Alchemy listed off are not necessarily the same at every company. The workflow is different at every company. Also, I can assure you that designers are much busier than you make them sound and people from all over the company can make contributions. I've seen programmers come up with great gameplay elements and artists offer tweaks that help balance a multiplayer title. I've also seen designers heavily involved in certain other aspects of projects. In short, its a much more dynamic process than you make it sound.
Obviously companies aren't going to let their design team sit around doing nothing, but what you end up doing during the main production cycle depends on how high up you are on the design chain. Obviously Level Designers are busy actually building levels through in house dev tools or maybe third party tools, while the higher up on the chain you go the more of a management position the designers tend to fall into during the main production cycle.
Again, not every company is the same but I would imagine a large company like Nintendo has everything boiled down to specifics after the design phase is finished.