This morning I came across a great example of Emergent Markup Languages I posted about in the past while scanning through Marc's blog.  In a post about social webware  and Burning Man, I saw this paragraph:

We'll have to provide a small extension to MT so that MT can help people semantically tag their blog entries with <want> and <have> as well as <geo:Point> and <geo:Time>.

Wow.  What a powerful pair of emergent meta tags or metags.

Update #1: A recommended reading, Sean McGrath's Zen and the Art of Motorcycle Manuals.  Thanks to Phil Wolff for the reminder.