Consider yourself warned: the PlayStation Network will be undergoing maintenance in just a couple of days, on the 23rd June. Fortunately for us lot here in the UK, the timing isn't too bad; the PS4 maintenance will take place in the morning, from 06:30AM until 08:30AM. However, that means the service will be tinkered with at night in North America, from 22:30PM PT (the 22nd June) to 00:30AM PT, or 01:30AM ET to 03:30AM ET.
During these two hours, you won't be able to access account management, PlayStation Video, or the PlayStation Store. If you already have a PlayStation Network account, though, you'll still be able to sign in and play online games, as per usual.