I feel quite strongly that GameDev should cover all aspects of "game development" (note the site isn't called "game design"), which should absolutely include programming. Just because there's another SE site that already covers some related topic (i.e. SO in the case of programming), doesn't mean that the content doesn't belong here.
My reasoning is that although the content of two sites may have some overlap, the audiences may not. If I want to know about a specific DirectX API call, or tips on doing efficient 3D matrix transforms, I'm much more likely to get a relevant/complete answer from professional game developers than I am to get them from a broader programming audience (even though they're "programming questions").
My feeling is that GameDev should cover questions relating to:
- Game design (architecture, gameplay, ideas, mechanics, etc)
- Game assets (creation, storage, editing, etc)
- Game programming (coding, bugs, best practices, patterns, etc)
- Game development (testing, team development, tools, etc)
- Game release (hosting, publishing, etc)
- Game industry (careers, trends, technology, etc)
However, I do agree, that at some point there will be a line where questions become too general and are probably better migrated to SO (or some other SE site). Basically we need to come up with a nice simple single rule that we can apply objectively to a given question to determine whether it's on/off topic. For example, on SO you can apply the question: "If I replaced the word 'programming' with the word 'knitting', would this still belong on SO". (so "What music do you listen to while programming?" is a bad SO question since "What music do you listen to while knitting?" is clearly unrelated to programming).
For GameDev I think that defining question is: "Would a professional game developer give me a better/different/more specific answer to this question than other programmers?". For example if I'm asking about a specific game engine API, then SO is probably not the best choice, since it's unlikely you'll find enough people with the right exposure (different audience). If I'm asking about, say, a path finding algorithm, SO is probably not the right choice since if its for a game, you'll probably trade off some accuracy for more efficiency (different needs/goals). But if you're asking how to reverse the order of an array, then a game developer is going to give the same answer as any other programmer, so it probably belongs on SO.
Buy hey, that's just my 2c... I guess we'll see how the votes turn out.