Why is Meta.Stackoverflow.com called "[StackOverflow's] Feedback Site" in its automated e-mail signatures? What exactly does 'meta' mean in the sense that it's used, here? It's a little confusing because the word 'feedback' isn't the first in my mind when I think about meta. There are only 63 articles tagged 'feedback', and Hell, I got more than 63 feedback items sitting on the tip of my tongue. Don't make me get my backlog.
Meta- is a prefix used in English (and other Greek-owing languages) to indicate a concept which is an abstraction from another concept, used to complete or add to the latter.
In epistemology, the prefix meta- is used to mean about. For example, metadata are data about data (who has produced them, when, what format the data are in and so on).
So it's a site about another site. In this specific case, Meta Stack Overflow is not only about Stack Overflow, but is used as the base for the entire Stack Exchange network.