The first time Google pushed through a quality score update that included the landing page factors, there was bit of an epidemic. Google last night announced that a new algorithm will be hitting us shortly. Two main things with this update.
(1) This will impact AdSense Publishers big time!
We'll begin incorporating landing page quality into the Quality Score for your contextually-targeted ads, using the same evaluation process as we do for ads showing on Google.com and the search network. Advertisers who may be providing a poor experience on their site will notice that their traffic across the content network decreases as a result of this change.
(2) They are updating the current algorithm, so some changes will go into affect.
Second, we're improving our algorithm for evaluating landing page quality and incorporating landing page content retrieved by the AdWords system.
So both sides of the fence need to be prepared for this update.
We discussed ways ways Improving Your Google AdWords Quality Score in the past.
Forum discussion at WebmasterWorld and Search Engine Watch Forums.