Citing Wikipedia (Redux)

A couple of months ago I posted about the propriety of citing Wikipedia as a definitive source on anything. In the process of arguing that it was OK in some contexts, I said:

But, sometimes, you just need a cite for something tangentially relevant but not super important. I don't think I've ever used Wikipedia in a brief, but I cited Mapquest directions before to show the distance between two addresses that, while commonly known to the parties and trial court before which the issues was first argued, surely weren't know to the judges in Richmond.

Turns out I was wrong. Today I was working on a petition to the US Supreme Court of a case we lost in the Fourth Circuit. The factual scenario that led to the conviction started off with an AMBER Alert. How it works and what it is really isn't critical to the case, but I felt it was important to drop a footnote explaining what an AMBER Alert is, so I cited to the Wikipedia entry. I carried that over to the cert petition as well.