What is a "featured topic", and why can't I post in it?

For instance
http://prince.org/msg/7/267254

"featured topic" means it was or is posted on the front page of the site as a news item.

as for why the thread won't allow any new posts, i have no idea. once in a great while there's a site glitch and a thread will decide it's done and lock itself. i poked around at that thread - no mod locked it and i could not get it unlocked. sorry about that.

Hmmm... I thought it auto locked after a certain period.
I noticed that thread was started April 11 and was inactive for at least
a month before it was brought up again.