If a moderator views a flag on a post, but doesn't act upon it, the post will subsequently be faded when the flag queue is viewed. For example, this is how it looks in Chrome (Firefox is the same):
On Opera 12.02 (Windows 7), the fading does not occur:
I'm not sure if this affects other sites, but my guess is that it might. It also appears to affect the 10k flag queue list.