The maintenance starts at 8:30am PST (4.30pm BST) and will go on until about 8.30pm PST (4.30am BST, June 10th). No PlayStation Store.
Don't expect to go managing your PSN account either, although you might still be able to sign in. "Maintenance is expected to start at 8am Pacific and will last for several hours, until approximately 8:30pm Pacific," posted Patrick Seybold on the .
"During this time, users won’t be able to access the PlayStation Store or Account Management, and may encounter some difficulty while signing in to PSN." You'd best squeeze what you can out of it before the 12 hour blackout. It's unclear if this will affect the European PlayStation Network, because it seems to be US centric.