[kentonv]

It usually means this is an experimental side project of some Google employee, and not an official part of any Google product strategy. Google likes for its employees' side projects to be released under Google's GitHub org, which you can variously interpret as good (Google wants to promote and support open source experimentation) or evil (Google wants to assert ownership of its employee's side projects) depending on how you feel about Google.

(I used to work at Google and had a lot of side projects. That was before Google moved everything to GitHub, but they liked for me to mark the code as copyright Google but "not an official Google product". I was fine with this arrangement.)

[userbinator]

or evil (Google wants to assert ownership of its employee's side projects)

I believe these are still worked on company time, in which case it is absolutely normal for Google to claim ownership.

[kentonv]

Some are, some aren't. Google wanted me to assign copyright even for projects that I worked on entirely at home. There's an additional process you have to go through if you don't want to assign copyright. Personally I didn't care since it's under an unencumbered open source license anyway, so it hardly makes a difference.

(To be clear, I meant the good/evil thing to be tongue-in-cheek...)

[userbinator]

for projects that I worked on entirely at home

That's... disturbing, and all the more reason to keep your work and private life strongly isolated. Suppose outside of work you write scripts for various things and distribute them online to friends and so forth, or blog posts, etc. Your employer should never be able to claim ownership of that.