Its gotta be the app itself. It could poll off the update interval settings in the app, I think its 1-2 hours by default. The only notifications I get are messages and chats (push) nothing else.
I seem to be getting messages and chats just fine too, but it doesn't notify me for example when someone replies on one of my status updates or on someone elses update that I have commented on.
I know it should work that way because on my GF's Droid 2 it works.