I believe mod development and map editor questions should be on the Game Development wiki, given a choice between the two. If both Gaming and Game Development flourish, I think the development side of gaming should be entirely contained within [the game development] site. Since modding is the development of a game modification, it is inherently more appropriate for the Game Development wiki.
I would say this even extends into Lua scripts for World of Warcraft and any analogue in other games. Since that is entirely about the development of game tools, the game development community would be more suited to fielding these questions.
The underlying reasoning behind this view is that pretty much any discussion about modding or scripting is going to boil down to two things: questions about tool sets and questions about programming. The Starcraft II map editor is a tool set; it allows a person to develop custom maps only for Starcraft II, but isn't that the same purpose as Unreal Editor or Hammer? Since many tool sets have features that have the same verbiage or wording that is very close, experienced game developers will be the more expert people to answer these questions.
I agree with tzenes in that the Gaming wiki should be about gaming. This includes:
- Questions about tips, tricks, and strategies for specific items of gameplay.
- Questions about the hardware and software accessories for a game or system (I would include things like PunkBuster or TeamSpeak in here, as well as controllers and other hardware).
- Questions about mods, like DoTA, as they are games in their own right.
Hopefully that helps define more of what I am thinking the Gaming site would be good for.
I'd like to see this be the Anti-GameFAQs, where people go to find answers to their questions as opposed to pouring through long, albeit useful, FAQs to find a simple answer.