I really have only one suggestion: mandate (or strongly encourage) posts to be tagged with a Rails version (or a tag like "not applicable to a version" if that's the case.) One of the things I find most frustrating when searcing for Rails topics is finding information that is relevent to older versions of rails but no longer applicable to what I'm using. Since Rails is a framework not afraid to break backwards compatability among major or minor versions (in fact this is the norm), having a version tag could be very useful in my opinion.
FWIW, StackOverflow seems to have a policy that assumes people will update their answers as new versions are released. From personal experience searching that site, I've found this seldom to be the case.
Anyway, not sure if others think this is important but it's something I think might be nice.