Official Google Blog: Introduction to Google Search Quality

> When an engineer gets a new idea and develops a new algorithm, we test their ideas thoroughly. We have a team of statisticians who look at all the data and determine the value of the new idea. We meet weekly (sometimes twice a week) to go over those new ideas and approve new launches.

This line has to make a lot of search startups more comfortable. In one sense it's scary that Google has so much manpower behind keeping their results high quality. But it's quite clear that they cannot adjust on a dime and try wild new ideas. This is where the agility of search startups can try out different approaches that might not "maintain quality" against legacy search results. It makes them a bit more iterative and hopefully some startups will make some interesting leap to get even better results.