To sum up where the Fediverse is right now:

1. @[email protected] backs it
2. The @w3c backs it
3. @fsf backs it
4. @eff backs it
5. Twitter Co-Founders @ev and @biz back it
7. Web browsers like @mozilla and @Vivaldi back it
8. Prominent 3rd party client devs like @paul backs it
9. @gruber and @davew back it
10. @georgetakei backs it

Am I missing anyone?

Oh yeah, YOU back it!

You are missing projects that already are (WP) or in the process of (Tumblr, Flickr), or the sites adding Fediverse widgets, supporting the AP protocol as they join the Fediverse. Of note are the devs of various projects and apps... the Fediverse would not exist without them! It's been evolving as a decentralized social media network since 2010, six years before Mastodon.
@shelenn There's lots of things I'm missing.