[farlington]

> What is the usefulness of this information?

My guess is that it's there for the sizable population of facebook users who check it compulsively. For a lot of people, the appearance of constant activity is going to be a lot more interesting than the appearance that nothing is happening, even if for only fifteen or twenty minutes. I can see this increasing 'engagement' a lot, and it's easy enough to ignore for people who find it annoying.

And your optimal signal-to-noise ratio is still there in your news feed.

[cgranade]

But it's bad for compulsive checkers, too, in that it doesn't let you peruse every item in order like the old News Feed design did. It's a ticker, and so far as I can tell, that means that when you miss an item it's gone.

[farlington]

You can still do that if your news feed is set to show "Recent Stories" and not "Top Stories". The mini sidebar is mostly stuff that hasn't been in the news feed for years, like when your friends comment on or like other friends' posts.