As anticipated, Apple has released its major update to iOS, iOS 5, to the masses today. New features include the Android-style Notification Center, BBM-style iMessage, iCloud, Reminders, Wi-Fi Sync, and Twitter integration. Sadly, Apple's all-new Siri personal assistant is limited to the iPhone 4S. The rest of the features are available on the iPhone 3GS, iPhone 4, iPod touch 3rd / 4th generations, and both iPads.