It seems many new sites which ranking just climbed up around 3 weeks ago or so got dropped in ranking. But it not penalized or anything. Because not only me but 10 of my competitors ranking just dropped out as same (to #100+). However, ranking for allinanchor, allintitle in all DC's still the same for me and my competitors. I see many sites which is old and some are never updated or do new link comes up to top 20 or even top 10 which many of them are out of top 50 or top 100 for a very long time. This look like some kind of roll back. Some of my old sites are not effected. They can maintain their ranking and some just climbed up. I had seen this happened before at the beginning of Jan 2008 and then came back to normal and now it's happened for 3 days ago until now. My opinion, if your site ranking in Google DC's directly is fine then you are still fine. Don't worry too much for Google.com search results in USA. What is your opinion guys?