Large patent portfolios owned by big companies represent the most danger for small companies trying to make something new. Big companies can afford to fight each other with armies of lawyers and settle on large piles of cash. However, if your startup gets a threatening letter from Google telling you that you are infringing on their patent, you are done. Google is a public company, so they have an obligation to their shareholders to turn their investments into profits. Hence, I don't see any reason, why Google's lawyers won't google through their newly acquired patent database to see how they can extort some juice settlements or shut down some small players.