When you wake up tomorrow, the world will be unrecognizable: Muni is adjusting the behavior of several lines! We made an easy-to-look-at map to help you figure out your changing landscape. It only took us about half and hour to do -- why didn't Muni make such a map? Because they're lazy! Ha ha ha, just kidding, of we all know Muni isn't lazy. Feel free to speculate in the comments what the real reason could be.
As Greg pointed out, Muni is using posters to alert riders, which would be a great idea except that the posters don't actually describe all of the changes -- each poster only describes one or two of the changes, when in fact seven different lines are being adjusted. Muni could be using the NextMuni signs to explain those changes; the signs can be configured on a system-wide, per-route, or per-stop basis to show extra info. Stuff like, "this stop will be discontinued," or "new route change: transfer from this train to an N to get to Caltrain," or "the 47 is delayed right now due to an accident; take the 49 instead." So why doesn't Muni use the the signs to issue alerts? Because they're lazy! Ha!course