I knew it was only a matter of time. A company named Kinderstart has sued Google because their search ranking dropped. I predicted this sort of thing was going to happen, and I have to imagine it’s only the tip of the iceberg. Unless the rulings in cases like this go decisively in Google’s favor (ruling that Google can return whatever it wants in whatever order it wants), I expect we’ll start hearing about companies suing for higher search placements because they’re more "deserving" in one sense or another. Eric Goldman has a good breakdown of the legal aspects of this case for those that are interested.
The entire Internet will be watching these cases with interest, I’m sure.