Rated 3 out of 5 stars
Will it block Google, Facebook, Microsoft ?
I'm not sure I understand the relevance of this add-on.
Neutral 3 stars.
Not a full add-on
This proof-of-concept was created to spark some ideas on how Mozilla can protect users' data after sharing with web sites. Check out the blog post for more info: https://blog.mozilla.org/labs/2012/10/about-trackers-protecting-shared-firefox-data/
The sites that end up getting blocked depend on the sites you visit, and how they get blocked are different as well.