Yesterday Sony Computer Entertainment announced through a statement, that the Bloodborne servers would be down "a few days".
Luckily the wait wasn't that long at all, as the implementation of Patch 1.08 was faster than expected. The servers were restored minutes ago, so if you can't wait for From Software to punish you some more, you're in luck!
Reports suggest the reason for the emergency maintenance is pinned down as an exploit that allowed players to access the new expansion The Old Hunters without paying for it. Sony have not mentioned it, but if there was indeed an exploit to access the content without paying for it, it would make sense that the servers were taken offline.