Question : Sudden drop in Google ranking

Hi, I have been reading that google have been adding some tweeks to their algorithim over the last few weeks.  And our site has lost 30% of its back links on google. BUt then so have our competitors...And we are still ranking fairly high on most of our keywords.  But one for one keyword we have been going up and down like a yoyo...There are the most competitive of the keywords we need ranking on...

Does anyone know anything about what google are upto over the last month/few weeks?
IF there isn't anything going on, why would we yoyo on one set of keywords but not others?

Answer : Sudden drop in Google ranking

Google is constantly tweaking its algorhythms.  They are in an ongoing battle with people trying to get rankings they don't deserve.  There is really no way of knowing how many backlinks you have in Google, as they don't share all of that information.  Yahoo is generally accepted as the site to check your backlinks in.  You also don't "lose" your backlinks, all you lose is the value of certain backlinks, as google devaules them based on a number of factors.

Google also has separate criteria for ranking for different keywords.  The rules for ranking for "real estate" aren't the same as ranking for "funny videos'.  That is why only certain keywords are being affected.

But to specifically answer your question, there was a Page Rank update on April 30th, so as the Page Rank of your backlinks changed, so did your rankings.