I highly doubt Google did any quality update yesterday, as they said updates like Penguin aren't happening until next year but with core search algorithms, those are constantly being tweaked.
The last update we saw was around December 16th and this was not a confirmed Google update.
Now I am seeing some chatter around a December 29th Google update. Here are some quotes from the ongoing WebmasterWorld thread:
I am not sure what happened but yesterday I got a small uptick in traffic (about a 8-10%) and a big boost in conversions (about a 40% increase). I normally see a small uptick for both right after Christmas but nothing like what I saw yesterday. Did anyone else see this?
Saw the same thing -- had a good string of sales come through at about the same time. Guess this is the way it's going to be from now on... I suppose the non-zombie day is somewhere around sunday-monday at the moment.
Our Google traffic has jumped sharply in the last few days, compared to the same days of the week earlier in December. Daily revenues are way up, too.
Ditto what EG said.
Xmas was nice, but it's good to see intent ramping up again for what we sell.
Have you seen any changes this week in your Google traffic, outside of the holiday/new years stuff that is expected (of course it is hard to isolate patterns during the last week of December).
I did ask a few SEOs, especially Glenn Gabe who follows Phantom closely and he said:
Forum discussion at WebmasterWorld.