On 17th January 2013, we have seen major effects on Ranking, Traffic, Results and so on and till now no-one knows what`s the matter behind this.
Some of the views are here which i collects form different websites, analyst, blogs...
1) Google is pushing the search query towards the brands, and less towards lesser known brands, people or things.
2) Panda updates is not there on 17th but its Google update which called " Link Devaluation" Google not confirm officially but its true that Google just rolled out "Link Devaluation" update on 17th Jan 2013 and that's why ranking fluctuation is there.
3) There was a glitch on 17th January, something wrong in the Google algo, now to fix it they are re running the previous panda script and to cover it up they are calling it panda refresh.
4) Google Announces 24th Panda Refresh; Not Related To January 17th
5) Google is promoting all ".com" websites in Google.co.in (Google India)
May be....Google is promoting all US companies. US government might asked Google to help improving the US companies.