I noticed the same happening to me with two sites on Jan 24, I use to be in positions 6 and 7 for main keywords on each site. then on the Jan 24 my positions moved to page 6 and page 7, my long tailed keywords went up, overall my hits to my sites are up 20%.
I first noticed the kw postion decline with a site that I was building some backlinks for, I immediately thoughts Oops. I did someting wrong with that one site, then I noticed the exact type of kw decline with a site that I hadn't touched for a long time..
After looking into webmaster tools, it said that I had in excess of 2,000,000 links from one of my other sites where I had placed links within the footer of each page pointing back to me partner sites using the same keyword that google killed me for. I am now assuming that because google nailed both sites that the problem must have been with the links back to these site that I had within the footer.. and have now removed them, I thought that have links in the footer didn't account for much, but I am now assumming that google considered this a No No..
Also I'm not sure where google ever came up with 2,000,000+ links as the site for sure doesn't have that many pages... thus that many footers with links in them.
Anyway I would be interested in hearing anyones thoughts. I also noiced that one ofmy competitors whom clearly buys many links and has a blog roll in his site going on for hundreds of pages with the exact same content with the exception of changing the city name withiin then title is now in a better SEO position then I, it seems hardly fair that google doesn't seem to take hit site into account... < continued here [webmasterworld.com...] >
[edited by: tedster at 5:42 pm (utc) on Feb 1, 2012]