Apple senior VP of iOS, Scott Forstall, just announced iOS 5 and it comes with 1500 new API for developers and 200 new features for users -- including notifications, lock screen info, Newstand, Twitter, and more!
Notifications: Looks a lot like LockInfo, aggregates all notifications and you swipe down from the top to get them. They're non-obtrusive. Fade in to alert, then fade out and you can get back to them any time.
Lock Screen info: Looks like MobileNotifier (which is probably why they had to hire Haas). Swipe to go to voice mail, SMS to go to conversation view, etc.
Newstand: This is an app, integrated on the home screen, that automatically collects all subscriptions into a folder so you can access you magazines
Twitter: Deep integration provides single sign-on. Twitter gets added to the action button and is accessible in a lot of apps. Integration for contact photos as well.
Safari: Reader, Reading list (Instapaper was smart to kill the free version!), and tabbed browsing
Reminders: Basic To Do functionality with built in calendar support. Task managers just got Sherlocked...
Camera: Take a photo without entering passcode, use volume up to take a picture, pinch to zoom, photo editing.
Mail: Rich text entry. Indents. Flags. S/MIME.
Dictionary New, system wide.
iPad portrait keyboard: Split screen to save your thumbs!
Tether-less setup: PC-free, post-PC, call it what you want but Apple has cut the cable
OTA updates Apple is really doing bit dif/delta updates for apps! (Georgia can opt out, though)
Game Center: Achievement points, find friends, friends of friends, game discovery, turn based games, game downloads.
iMessage: Cross iOS messages. (What, iChat was taken?!) Essentially BBM for iPhone and iPad. Text, photos, video, contact info, group messaging.
Wi-Fi sync: Yes, finally, iTunes sync without the tether