Most people's "public timeline" is simply the primary stream on their homepage.
Screenshot from ~2012-07-26, mere months before Twitter shut down their public timeline feature.
The various GNU social instances often show a public timeline,
and also have a "Whole Known Network" which connects multiple instances per hope “it's supposed to be "all people in the instance and all people they follow to one degree" but the networking isn't working for whatever reason.”
public indieweb notes stream
It might be useful (as a "here we are now" obvious demo) to put up a non-auth'd public stream of indieweb notes.
E.g. what if we showed a stream of notes from the homepages of everyone who has signed into the wiki in the past year?
And displayed that stream of notes somewhere on the indiewebcamp home page. Just the notes (so not a planet, but more like the old Twitter public timeline).
- +1 Aaron Parecki “that'd be fun” 
- +1 Ben Werdmüller “I really love that idea. A hub for people posting notes to their indieweb homepages”
- Malcolm Blaney set up https://unicyclic.com/indieweb based on this irc discussion.
- +1 Ryan Rix (rrix)