Yes, somewhat. Anything shareable. The major point would be the github-like financing model: It's not the individual users that pay for the service by enabling targeted ads but companies that want to get in contact with potential customers on their page. It seems like a minor difference but would have quite strong effects on user privacy - there would not be a need for ever more tracking of every online activity.

Ello recently tried this, and they're still making good progress

For me it's more like twitter that anyone I know actually uses.

More like Facebook is to RSS what HTML email is to plaintext.

I don't find Twitter is at all useful for keeping on top of interests.

..That would just be Tumblr