Here's a post explaining Google's support for just seven open source licences:
The trend around licensing is obvious: GPLv2/GPLv3 represent 42.6% of the projects, and Apache is 25.8%. MIT, BSD, and LGPL are at about 8% each, Artistic at 3.5%, and MPL 1.1 at a mere 2.7%. This follows my own observation about how people license their projects. If they are advocates of Free Software, they will choose GPL; advocates of Open Source will choose Apache (a more modern and thorough permissive license, compared to BSD or MIT). And this is exactly what I recommend to people: choose GPLv3 or Apache v2 based on your personal philosophy.
Well, actually, there's another rather important trend that is conspicuous by its absence: adoption of the Affero GPL. To which Google seems strangely allergic....