I haven't gotten a new activity pop-in for a while. Not sure when this started.
I don't usually use SO but I went over there because I know that they have constant new activity and I still am not getting the notices. If you see in the screen shot below, I'm pretty sure that SO hasn't gone five minutes without activity in a while... particularly not at this time of day. But, no new activity pop-in.
The Alpha Two post says this:
Real-time notifications
Most tabs should have real-time notifications now, including the "need answers" pages, and pages filtered by tags (with "any" or "all")
But I'm not sure if the new activity notices are what the post is talking about.
I'm trying to determine if this is a bug or if it's just me.
Just for my info, I'm using FF 30.0.5 for OSX.