My snap judgment would be to say that questions that are phrased in a way that the discussion can any solutions can be applied by others confronting the same issues should be encouraged through the normal mechanisms (up voting mainly). For those questions that are too specific and non-applicable to the rest of the community, those questions should naturally be viewed less and receive less votes giving them the treatment they may very well deserve.
I agree with others as well who make the point that when diagrams, screen-shots, and other useful illustrations are included these questions have a particular degree of usefulness to the community regardless of how widely it applies to others since it helps promote deep and higher quality discussions. In these cases there is almost always something that others can take away from the discussion even if it isn't the main topic being discussed.
NOTE: In the past I thought the community wiki feature? that I've seen on StackOverflow was to be used as a way to pose more broad questions that promote discussion but do not necessarily elicit a single precise solution to a problem however it appears this may not be the original intent. The topic of discussion here however is about questions that are overly specific to a degree that they may not be very useful on a large scale to others in the community. Also community wiki posts are mainly used to hand over ownership of a question or other post to the community.
