Sometimes it's government policies themselves that unbalance the market and allow the proliferation of monopolies. I'm not sure it's the case with Google, though. Would appreciate a comment from someone more informed.
The answer is no. There aren't any significant policies (related to internet search, crawling or intellectual property) which create a barrier for little guys but which Google has the resources to handle (which is usually how regulation stifles disruption, sometimes by design).
Don't underestimate the EU though, given some of the ignorant tech regulation they've already passed, it could happen at some point.
As Bing has demonstrated, Google's dominance in search is a result of superior technology and a huge lead. Even a company with the resources of MS hasn't been able to do anything but follow behind and create almost good enough copies at each step.
Although to be fair that's what MS has always done so maybe a more nimble company might have a shot some day.
In the near future AI and machine learning coupled with computing advances could be a way into search for competitors if G doesn't get there first.
I would be interested in more information about this too. Maybe we can start with intellectual property, for example maybe Google patents that are enforced by governments laws and justice are a huge barrier of entry for potential competitors
