I noticed on SO earlier that clicking on any of the various live refresh links causes the permalink button on the bottom left of a post to misbehave. I specifically noticed it with:

• The this post has been edited link
• The this post has new answers link

After using either of those to reload a post, clicking the link button on the post will cause the little permalink popup to fade in like normal, but then immediately fade out, meaning that it's not possible to actually copy the URL.

I saw this on Firefox 12 (Win7) and Chrome 19 (OSX). Performing a manual refresh of the page fixes it. It was reproducible with all of my userscripts disabled.