At the risk of sounding controversial...
... I don't agree. Yes, the idea that Google isn't the "dominant" search engine is ludicrous. But so what? Does that mean Google has a responsibility for smaller companies, to stop them going out of business?
Google made a competing product (which may or may not have been better than the competition). It promoted its own product, ranking it higher on its own network than those of the competition. The competition subsequently lost market share.
This is just business. Build a product. Promote the product effectively. Grow the business. Eat up or destroy the competition. If you're clever, gain monopoly status (or get close to it). If Google had used underhanded tactics to take down Streetmap then fair enough, there's a case to answer. But simply promoting its own product over the competition, on its own website? I'd say that's just tough titties.