Google Inc., long considered the gold standard of Internet search, changed the secret formula it uses to rank Web pages as it struggles to combat websites that have been able to game its system. On February 24th Google announced (
http://googleblog.blogspot.com/2011/02/finding-more-high-quality-sites-in.html) the change to its mathematical formula in order to better weed out "low-quality" sites that offer users little value. Some such sites offer just enough content to appear in search results and lure users to pages loaded with advertisements.
The Silicon Valley company built its business on the strength of algorithms that yield speedy results. The company constantly refines those formulas, and sometimes takes manual action to penalize companies that it believes use tricks to artificially rise in search rankings. In recent weeks, it has cracked down on retailers J.C. Penney Co. and Overstock.com Inc. Last month, Google acknowledged it "can and should do better" to beat back sites that "copy content from other websites" or provide information that is "just not very useful" but are ranked highly anyway.
Most people have nothing to worry about. What Google is doing is getting rid of lousy, irrelevant, top-ranked websites. That's a good thing.Websites that are not 100% relevant to a search, websites that are top ranked because of keyword stuffing, and websites that were made only to promote paid or sponsored links (i.e. Google Adwords) are all on their way to the bottom of the heap.
You probably have nothing to worry about.Here is a reminder of what Google likes and what it takes to get top ranked and KEEP those rankings.
1) Google likes websites and pages that are the MOST relevant to the search performed by a Google user. In other words, if your pages create the most desirable and informative page that matches a search - you're in the game!
2) Google doesn't just look at one page to determine relevancy, it looks at your entire website.
3) Google Webmaster Tools (
http://www.google.com/webmasters/) help you determine what Google thinks your website is "relevant" for.
4) Google absolutely hates when you try to manipulate the index or "cheat."
5) You can't just "stuff" keywords on a page and expect that to work. Weave your keywords and keyword phrases into your page copy. It's not easy in all cases, but it (a) has to be done, and (b) works very effectively.
6) Page-title tags are still critically important to the entire top-ranking process, but they are not the only factor.
7) Inbound links from other thematically similar websites and blogs have a tremendous amount of value when it comes to (a) getting top ranked at Google, and (b) staying top ranked. Remember though, it's not about the quantity of links but the quality of the sites linking to you.
Resources:
Wall Street Journal and Chris Jaeger,
Internet Marketing for Wedding Professionals 
