Google announced recently some changes that could affect advertisers and I really like how it was explained here
The article explains in detail the changes and how Google will no longer show its long-standing strip of adverts to the immediate right of search results.
It goes on to say that with the sidebar ads axed, fewer placement opportunities will lead to greater competition for the coveted top spots. More competition will more than likely mean that prices will go up.
The article also explains the repercussions for organic search. Worth a look here.