Good ideas and conversation. No ads, no tracking. Login or Take a Tour!
I think the stream of comments from people you follow doesn't serve an actual desire, whereas this would. I often want to know about activity in a specific post I've seen before, and want the ability to quickly jump to it.
I think this would be a great feature for hubski at the current density of users. It's a feature that increases in attractiveness when the user base isn't too large (large trafficked posts don't really need activity alerts, because there is always activity, though not all the time), but facilitates increased participation of that base. I think it's worth considering.