Google Adwords is releasing a new feature that will override the setting for "Ad Rotation" to optimized to show the ad that receives the most clicks after 30 days. If you have your ad rotation setting on anything other than optimized you will have to go in and update it every 29 days if you don't want Google automatically changing your settings. 

I'll bet Google's profits go up after this change rolls out.

Here is the full link for this article:
http://adwords.blogspot.com/2012/04/new-changes-to-ad-rotation.html

If you want to make it big through online marketing, then it is important for you to hold as much information as you can about pay per click search engines.  As they always say, “He who holds the information holds power”, and pay per click marketing is no exception.  Winning over your own goals and competitors take not just great effort from you, but all the right effort to do things right the first time.

The truth is, you have about hundreds of choices for search engines that could potentially generate the needed traffic for your site or any landing page.  It becomes a challenge as the number increases and it gets more and more difficult to identify which among these would be worth investing time and money in.  Thus, it is always healthy for your business to concentrate all initiatives on the top ranking search engines, unless of course you have a very targeted audience.

Maximizing Ad Performance In Pay Per Click Search Engines

It is therefore important to identify the key characteristics of your target audience in order for you to be able to effectively narrow down your prospective list of pay per click search engines.  However, if you have not yet really done that part, it is safe to assume and recommend that you pick the top search engines according to my own experience in PPC as well as the feedback from other users.