It seems like Google had initiated a major update to it's SERP last night, with a lot of site-owners experiencing a lot of change in the Google Search Engine Result Pages. Speculations floating around forums indicate that, it might one of legendary Google Dance.
Google Dance: A few years ago whenever Google modified it's ranking algorithm, it often started to show up slowly across data centers and displayed different results. This indicated incoming changes.
There has been a lot of noise regarding this issue at Webmaster World.
Some of the comments are really interesting:
"It would appear we are in for an old style Google shake up . Sites formerly at no. 9 and 10 are now no. 1 and 2, and vice versa! "
"I am seeing a 2003 CNN story at #10 on a two word term. This follows several days of seeing a 1997 text file showing up in the top ten on two different, but related, single word terms. I haven't seen stuff like this since Florida."
"Didn't they say a while back they are filtering subs from the same domain? I'm seeing multi sub-domains in the top 10 all over the place."
"Most of my competitors have been hit the same and my SERPs are generally an irrelevant mess of shopping sites or single pages with absolutely no information on them apart from maybe an image and a couple of keywords…mess, a total mess."
"A lot depends now on when the data-centers have cached your page, I've got half of the C-Blocks with a cache of my site dating March 20 ( lower rank)the other half dating from the 23rd onwards with a higher ranking for my site. I'd recommend sitting tight as well until everything settles down."
So, it's still very confusing to comment, either Google is updating it's SERPs or it's just doing another of it's Google Dance.