I know the features wouldn't be installed until this SE makes it out of the public beta. But in the event that it does, I think that this is something that we should be prepared for.
What would the criteria be for deciding if a question would be left here, or suggesting it be on Stackoverflow?
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:
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.
I see no reason why programming questions can't be here as long as they are related to game development. Saying this site should be for theory only, and not practice could really be hurtful.
I am sure you could find an answer to a programming question on SO, but you could possibly get more, and better answers here. We are the professionals, right?
Why wouldn't we want programming question here? Would it be harmful to allow them?
I would personally prefer a lot that only game development specific questions are asked here, not general programming ones.
Moreover, when asking such question, I will definitely be asking it on SO and not here, because there is a lot of smart people in the general programming which are in no way related to games, and I would not like to avoid the chance of getting the answer from them.
About game programming, i think there are questions and topics that should stay on gamedev.SE if they are specific to game programming, some examples:
3D programming and/or maths that some programmers would be horrified by.
Design Patterns: well they are not specific to game programming, but if the question has a context about game programming, why not.
Optimisation: well it depends, because on SO it seems there are some strong C language advocates who will bash C++ because they do embedded systems or system programming, but in the game industry we need high level and speed, and also because well, most of the industry now works with C++, so I think it stills belong to gamedev.SE.
I think that this site should be more theoretical rather than practical. There are numerous sites, such as SO that will answer any coding question you have but not many that will help you with the theory behind game design/development etc...