In epistemology, the theory of knowledge, the prefix meta is used to describe about (its own category). For example, a metablogger would be a blogger who writes about blogging.
As someone who spends a great deal of time as contributor, participant and observer of a pretty diverse array of web communities, I find the meta aspect fascinating. What I mean by this is without fail, every community enjoys having discussions about itself. It’s something not usually stated directly within the communities, but it’s a reality.