Update 11am ET: Logins appear to be working again for the iPhone Dev Center, at least from the East Coast. If you're still having trouble logging in, try using Firefox rather than Safari. Still hearing reports of intermittent issues (Namely "Can't connect to application instance")
Isn't it weird that Apple has taken down the iPhone devcenter a day before their big "newest creation" announcement? Normally we expect site outages on the day of announcementpalooza, not the day before. Maybe it's a maintenance/infrastructure thing that needs to go live and be tested before the big day. Maybe it's 3.2. Maybe it's an attack of rainbow unicorn puppy dog devs. We don't know. All we know is that the site has been down since about 5AM Eastern. (I write this at about 10:30 Eastern). iTunes Connect remains unaffected by this outage.