Earlier today I noticed that some of the Google Sponsored Links showing on the result page has a orange background.
http://googlified.com/files/orange-sponsored-links.gif
I am 100% sure that it's not a Firefox add-on, because it has disappeared.

I've seen this before too. I'm sure there's a thread knocking around in this forum about it. It really got my attention when I saw it. I guess their plan worked.

How strange! Google is using a color that they never use in their interface! Trying to increase their CTR?