Google makes changes to their search algorithm an average of once every 175 hours

With several hundred signals that are read and processed by their search algorithm, weve always known that Google puts a tremendous amount of time, money, and effort into making their results match their users needs.

Now, we have an idea of how much tweaking is done: a lot.

Source:
http://www.techi.com/2011/08/google-makes-changes-to-their-search-algorithm-an-average-of-once-every-17-5-hours/