Today happens to be a big day for Apple. No, not the release of the iPhone 4S – that’s Friday. Today is the day iOS 5 is released for the iPhone (3GS, 4 and upcoming 4S), iPad and iPod Touch (3rd and 4th generations).

What does iOS 5 entail? Take a look at this (incomplete) feature list:

• Notification Center: One of the most treasured features of Android finally comes to the iPhone. Swipe down from the status bar to get an overview of calendar events, app notifications, email, text messages, weather, stocks and more.
• iMessage: Apple’s answer to BlackBerry Messenger. Send and receive messages from friends using iOS 5. Group messaging, delivery and read receipts and seeing who’s typing is featured. iPod Touch users can utilize this feature too over Wi-Fi.
• Reminders: Not really a show-stopper of a feature, but a neat little app to keep track of your to-do list. Supports geo-location too, so you can set a reminder to show up when you go to a certain place.
• Twitter: If you love to tweet, you’ll love iOS 5′s new Twitter intergration.
• Photos and Camera Improvements: Double tap the Home button in lock mode to get a quick Camera button. Take a pic with the Volume Up button. Pinch to zoom. Edit photos and crop right on the Photos app.
• Wi-Fi iTunes Syncing and iOS Updates: Pretty much what you expect. Update your iPhone over-the-air and run iTunes syncing when on the same wireless network.

And many more, such as a Newsstand app. Running the betas for a few months, I’ve noticed this is a solid update. Well worth the upgrade if you’re running the 4. (I’m not sure about the 3GS but this doesn’t seem to be a processor-intense update.)

In addition to iOS 5, due in the afternoon on the east coast, Apple has fully opened iCloud.com and released the free “Find My Friends” app.

Source : Apple Releases iOS 5 with Notification Center, iMessage, Twitter, and More