Steve Jobs unveiled the newest version of the iPhone operating system at a press event in Cupertino earlier today. iPhone OS 4, which contains hundreds of new features and APIs, will be released to developers today and to the rest of us this summer. Jobs went on to showcase seven “tentpole features” of the new OS.

Multitasking

Apple had taken some heavy criticism for the lack of key features on the iPhone. In OS 3 they addressed the issue of copy and paste and finally, OS 4 brings multitasking to the iPhone, something that Apple’s competitors have had for a while now. It’s pretty clear that Apple has been working on this and was unwilling to release it until it was up to the company’s obsessively compulsive standards. “We weren’t the first to this party,” said Mr. Jobs, “but we’re going to be the best.”

With the new iPhone OS apps like Pandora will be able to play audio in the background, Skype will be able to receive calls even when its not open, Google Maps or other turn by turn navigators won’t lose track of your location while you change a song on the road, push notifications no longer have to go through a server, Facebook and Flickr can keep uploading your photos even when you exit and you will be able to switch between apps without losing your location within them. This last feature will be accessed by a new app switching tray that will be accessed by double tapping the home button.

Folders

Another complaint that users had about the iPhone OS was the way it organized apps. In OS 4 users will be able to create folders to organize their apps. By dragging one app’s icon onto another, a folder will be automatically created and named by an algorithm based on the category of the apps inside it. Users can create as many folders as they want. The icons for these folders can be treated as any other icons and can even be placed on the dock. No word as to whether folders can be nested or renamed.

Better Mail Client

The new Mail app will have a unified inbox where users will be able to view mail from all their accounts in a single place. It will also support multiple Exchange accounts, organizing messages into threads the same way OSX Mail does it and opening attachments using third party apps just like you can on the iPad.

iBooks

The iPhone’s new OS will include support for iBooks and the iBookstore. Books you buy on the iPad will be readable on the iPhone and vice versa and you will be able to sync your current page between devices much like you can with Amazon’s WhisperSync on the Kindle. As if that weren’t enough for the low price of your money, a two year contract and your soul Apple will include a free copy of Winnie the Pooh.

Enterprise

The iPhone has been a hit in the consumer market but it has yet to make a dent in RIM’s (maker of the BlackBerry) stronghold on the enterprise market. New features targeted at businesses include better data protection — with better encryption of emails and in-app data — mobile device management and wireless app distribution. Support for multiple Exchange accounts, as mentioned before, is new as well as support for Exchange Server 2010. The new OS will also include SSL VPN support.

Game Center

The new OS will have a social gaming network where you will be able to challenge friends to a game, find random people to play with and post your scores and achievements on global leader boards. This topic wasn’t covered very much so it will be interesting to see where this goes.

iAD

The last “tentpole” is Apple’s much rumored entry into the mobile advertising market. In what sounded like a message targeted directly at Google, Jobs talked about how most users get their data from apps rather than through “broad internet search.” The new ad platform will allow developers to include ads in their apps — hosted by Apple — that won’t take users to a browser but rather keep them inside the app so they are less anoying. Apple will take a 40 percent cut of the revenue generated by these ads.

The ads do look like a significant increase in quality from the what is currently available. They will be full screen, capable of audio and video playback and even menus and games. Some of the ads demoed looked like mini apps. They will all include an X in the top left corner to easily exit them and will be written in HTML5.

As a final note all of these features will be available for the iPhone 3Gs and the third generation iPod Touch this Summer. The iPhone 3G and second-gen Touch got a little less love — they will have some of the new features but no multitasking. The original iPhone got no love whatsoever. No word on wether it will support the update.