Some games require an online connection, stuff like Warhawk is obvious, but some of Capcom's downloadable releases require connection to the network at all times.
I am not effected by it either really, but the fact that no timeframe has been given is really not helpful at all. Sony themselves have declined to comment at all too, if I was really into the service I think I would be pissed.
I hope it comes back before Virtua Tennis 4 is out. I can see myself wasting so many hours on that online.