I want to develop a Q/A site with features substantially similar to Stack Overflow, but targeted to a different niche (electrical/hardware engineering as opposed to software engineering).
The code that runs Stack Overflow is not open-source, and from a previous mention of it on the podcast I believe I can assume it never will be. (Though UserVoice said "Wait 3-6 months and ask again")
I don't want to start from scratch as Jeff et al did, but I do want a Q/A site rather than a discussion site.
What framework or CMS would you start with to create this site if you were tasked with it?
I don't have an easy answer to this question, but you might consider looking at Kigg:
Kigg is an open-source Digg clone built on ASP.NET MVC. I realize this is different than StackOverflow, but it is still a user generated web site with an extensive comments, karma & membership system.
This might offer a good starting place.
You can always check out Coordino And use it as a base for your project. It is a PHP based implementation of StackOverflow
My suggestion for a framework would be Ruby on Rails (but of course with that you would start from scratch). Maybe you want to look into Insoshi.
Well the one that started it all is, of course Slashcode, the open-source software that powers Slashdot.org. There's also Pligg, an open-source digg-clone and a cursory google search will lead to many other similar open-source systems.
I'm having a go with Django, as I think something like SO would be great to have in work:
the Ektron CMS has a strong suite of community networking tools -- it may be a good place to start.