It seems as though Google are trying to increase their ad charges for those sponsored links in the top 1 and 2 position on their search results.

They have recently posted a message saying that in a few weeks they will change the formula that is used to calculate ad placement. Up until now this has been based on an auction against other bidders for the same keyword, and how good a match yourad is. However, in future you will be able to specify a 'maximum' bid for a search that will enable you to achieve a top placement based on a minium price for these positions. 

So, basically from what I can gather it will now not be possible to achieve these positions solely based on the quality of your ad and lack of other bidders. Instead, you will have to pay extra to get these positions based on the price Google sets for these positions.

I suspect this is just the start, and I bet we will see further 'hidden' cost increases in the future as Google starts to press its massive market share advantage to increase shareholder value.