So, first off, I don’t think anyone would object to you spearheading a dedicated Stack Exchange on PowerShell. I certainly wouldn’t.
That said, there are already dozens of places - including StackOverflow and ServerFault - where PowerShell questions are routinely asked and answered. Here, the TechNet forums, lots of spots. I’m not sure I personally see the value of Yet Another PowerShell Q&A Site, but that’s just me - if you see the value, then forge ahead ;).
I’ll offer this: While Stack Exchange’s format obviously works great in a lot of situations, it isn’t necessarily the best or only format. We get a lot of posts here, for example, that are asking “what’s the best way,” something most Stack Exchange sites prohibit. So I wouldn’t want to replace PowerShell.org’s forums with a Stack Exchange. And, while StackOverflow itself is obviously wildly successful, I’ve personally found its model to work less well with an admin audience (as on ServerFault); admins tend to follow-up less, so you get fewer answer votes, less up/down voting, and all the other things that make Stack Exchange “work.” Just an audience cultural difference, I think.
You’re certainly welcome to chip in here - we can always use more folks answering questions and offering alternatives and explanations to questions that have already been answered. It’s always deeply appreciated when people take time to help others!