Apple previewed iOS 5 all the way back in July but it is ready to be released today, 12th October. What should we all be expecting in iOS 5 though? Let's have a look and the main features.

Notification Centre

Apple’s new Notification Centre lives at the top of the screen and is accessible by pulling down the status bar. You can have full creative control over how your notifications are delivered and ordered. No longer do notifications annoyingly interrupt you when your busy, a bar quietly pops up at the top of the screen and then quickly goes away.

iMessage

Apple finally has a BBM-style group messaging client that allows you to communicate with other iOS 5 users. You will be able to sent send pictures, video, text, audio and contact information for free over Wi-Fi and 3G. The service checks to see if recipients are iMessage compatible, and automatically sends content using your network’s standard texting plan instead if they aren’t. Delivered and optional read receipts for messages are also part of the bargain as well as being able to see when a user is typing.

Newsstand

This is where Apple will be centralizing all digital subscriptions, including magazines like Popular Science and newspapers like the New York Times.  The goal was to have your magazines and newspapers all in one place to keep your home screen clutter free. Apple have delivered on this.

Reminders

A lot of us are busy people and need that extra help from our devices. Location-based reminders should help you remember to pick up you up some dinner when you're buy the supermarket. Geofencing will also send you a reminder when you're about to leave a certain place.  Reminders sync with Outlook, Apple’s iCal and iCloud so that they’re available across all of your devices.

Twitter

What’s one of the coolest features of iOS 5? Twitter, backed right in. You can now sign in to your Twitter account in the Settings app allowing you to share much much more with the world. Tweet a website from Safari, a photo for your Photos app, a video from YouTube.

Camera

A convenient update is that you no longer need to enter a lock code in order to use your camera if you have your device locked.  Other new camera features include pinch-to-zoom, single-tap focus, exposure locks and grid overlay. In the Photos app, you can perform edits like cropping, auto-enhance or red-eye removal, and create your own albums.

Safari

New to Safari is tabbed browsing, which is as it sounds. A really useful feature is Reading List/Reader view, which lets you save articles to check out later and strip away everything but the content for easier reading. Plus, as always, much-improved Safari performance all around.

PC Free and Wi-Fi Sync

You can now setup and manage your device completely from the device itself under iOS 5. No need to connect to iTunes, and with Wi-Fi Sync and iTunes Match, you won’t even have to make a hardware connection to transfer your iTunes music from your computer to your device. This may be the biggest step iOS 5 takes in terms of cutting ties with computing’s past.

Mail and Calendar

HTML-formatted composition makes its way to Mail in iOS 5, as does message flagging and mailbox folder management. Search body text of emails for keywords, too. These are more contributions to the Post-PC nature of iOS devices. Calendar also boasts new adding, renaming and deleting features for PC-free management.

Multitasking gestures for iPad

Switching between apps has never been easier on the iPad than in iOS 5, since you can use four- or five-finger swipes to rotate between open apps, and pinch zoom to close them. Swiping up also reveals the multitasking bar.

Game Center

New Game Center additions in iOS 5 include achievement points, photo sharing, friend recommendations and more, making it feel much more like Xbox Live, the gold standard in online gaming. Apple says 67 million users currently are active on Game Center.

iCloud

A huge part of iOS 5 is iCloud, which replaces MobileMe and provides free syncing of email, contacts, calendars and more for all iOS 5 and Mac OS X Lion users. Later, iCloud will also provide the ground work for iTunes Match, Apple’s cloud music service.