Apple has removed the old notification popup system for a more inline notification system, making it less annoying when you're watching a video or playing a game. The 'notification center' will act similar to Android, where your menu swipes down, revealing alerts for all of your phone, messages, emails and more.
The notification center is even on your lock screen too. The lock screen has received a major update, allowing for notifications from apps, messages, and even listening to voice mail without having to slide to unlock the phone. iOS 5.0 also comes with 'Newsstand', a new subscription-based application that has a ton of newspaper and magazine companies on board, including New York Times, SF Chronicle, Daily Telegraph, and more. Apple introduced a new Twitter integration for iOS 5.0, making it easier for users to post photos, maps, articles from Safari and attachments with a new 'Tweet' option [via TechAmok].