The Phantom strikes again! Google's Phantom menace! Alright, that's enough of that I guess.
Webmasters around the globe were wondering if an algorithm update occurred on February 7th. Google was unwilling to make comments, but studies by Glenn Gabe and Daniel Furch seem to indicate that it might have been Phantom again. You can follow the discussion about Phantom V on WebmasterWorld.
Phantom is Google's nebulous "quality" update. It checks for things like usability, ad placement, and general UX. Martinibuster asks, "Most if not all of the factors those articles discussed can be folded into Panda. Why are they making the distinction that it's something else?" That's a good question, imo. Gabe and Furch speculate that Phantom could be updating just like Penguin and Panda used to - on six month cycles, requiring a refresh for an affected site to escape penalty.
The more things change, the more they stay the same eh?