Apple today presented the new iPhone 4 featuring a new feature called “FaceTime” and a “Retina display,” the highest resolution display ever built into a phone. In addition, iPhone 4 features a 5 megapixel camera with LED flash, HD video recording, Apple’s A4 processor, a three-axis gyro and up to 40%.

All this comes in a new design of glass and stainless steel that’s purportedly the thinnest smartphone in the world. iPhone 4 comes with iOS 4, the newest version of Apple’s (renamed) mobile operating system, which includes over 100 new features and 1,500 new application programming interfaces for developers.

iOS 4 features multitasking, folders, enhanced Mail, deeper Enterprise support and Apple’s new iAd mobile advertising platform. iPhone 4 will be available in the US, UK, France, Germany and Japan on June 24, starting in the US at US$199 for qualified buyers with a two year contract.

“iPhone 4 is the biggest leap since the original iPhone,” says Apple CEO Steve Jobs. “FaceTime video calling sets a new standard for mobile communication, and our new Retina display is the highest resolution display ever in a phone, with text looking like it does on a fine printed page. We have been dreaming about both of these breakthroughs for decades.”

FaceTime lets you see family and friends anywhere there’s Wi-Fi. Using FaceTime is as easy as making a regular voice call, with no set-up required, and you can instantly switch to the rear camera to show others what you are seeing with just a tap, says Jobs.

Apple’s 3.5 inch Retina display has 960 x 640 pixels — four times as many pixels as the iPhone 3GS and 78% of the pixels on an iPad. The resulting 326 pixels per inch is so dense that the human eye is unable to distinguish individual pixels when the phone is held at a normal distance, making text, images and video look sharper, smoother and more realistic than ever before on an electronic display, according to Jobs.

He says the iPhone 4 is the thinnest smartphone ever — 9.3 millimeters — with an all-new design. The front and back are made of aluminosilcate glass, chemically strengthened to be 30 times harder than plastic, more scratch resistant and more durable than ever. The front and back glass have an oil-resistant coating that helps keep it clean, and encircling the iPhone 4 is a highly finished stainless steel band made of a custom alloy that is forged to be five times stronger than standard steel.

The iPhone 4 features a new 5 megapixel autofocus camera with a 5x digital zoom, a backside illuminated sensor and built-in LED flash that allows you to take pictures even in low light and dark environments.What’s more, it lets you record and edit HD video and the tap to focus feature now works while recording video. You can use the iPhone 4‘s LED flash for both still photography and video recording.

The new iMovie app for iPhone lets you combine movie clips, add dynamic transitions and themes and include photos and music, and users can buy it for US$4.99 through the App Store right on their phone.

Every iPhone 4 has a built-in three-axis gyro that when combined with the accelerometer provides six-axis motion sensing such as up and down, side to side, forward and backward and pitch and roll, making it perfect for gaming, according to Jobs. Developers can access the gyro using the new CoreMotion API.

The iPhone 4 comes with iOS 4. With multitasking, users can now instantly switch between any of their apps while preserving battery life. With Folders, users can organize their apps into collections by dragging one app on top of another. A folder is automatically created and named based on the category of apps selected. Users can change the name of any folder at any time. In addition, users can now customize their lock and home screens with an array of supplied wallpapers or with any of the photos on their phone.

The new iBooks app will be available for iPhone 4 as a free download from the App Store and includes Apple’s new iBookstore, which offers a way to browse, buy and read books on a mobile product. The iBooks app will sync your current place in a book, along with any bookmarks, highlights and notes you’ve created, between copies of the same book on your iPad, iPhone or iPod touch. iBooks users can also now read and store PDFs right in iBooks. There are now over 60,000 books available in the iBookstore, and users have downloaded over five million books in the first two months.

More than five billion apps have been downloaded from the Apple App Store and more than 225,000 apps are available to consumers in 90 countries. Almost 100 million iPhone and iPod touch users around the world can choose from a range of apps in 20 categories, including games, business, news, sports, health, reference and travel.

iPhone 4 purportedly delivers seven hours of talk time on 3G networks, up to 10 hours of web browsing on Wi-Fi and up to six hours on 3G, and up to 10 hours of video playback and up to 40 hours of audio playback. It’s powered by Apple’s new A4 processor.

The iPhone 4 features a second microphone and software to suppress unwanted background noise for improved call quality when in loud places. It also offers 802.11n Wi-Fi networking and adds quad-band HSUPA to provide 7.2Mbps downlink and 5.8Mbps uplink capability.

iPhone 4 comes in either black or white and will be available in the US for a suggested retail price of US$199 for the 16GB model and $299 for the 32GB model in both Apple and AT&T’s retail and online stores, Best Buy and Wal-Mart stores. iPhone 4 will be available in the US, France, Germany, Japan and the UK on June 24, and customers can pre-order their iPhone 4 beginning Tuesday, June 15 from the Apple Online Store or reserve an iPhone 4 to pick up at an Apple Retail Store. (Pricing requires a new two year AT&T rate plan, sold separately.)

Also on June 24, a new iPhone 3GS 8GB model will be available for $99. iOS 4 software will be available on June 21 as a free software update via iTunes 9.2 or later for iPhone and iPod touch customers.

iPhone 4 will roll out worldwide to 88 countries by the end of September. iPhone 4 will be available by the end of July in Australia, Austria, Belgium, Canada, Denmark, Finland, Hong Kong, Ireland, Italy, Luxembourg, Netherlands, Norway, New Zealand, Singapore, South Korea, Spain, Sweden and Switzerland.

iOS 4 is compatible with iPhone 3G, iPhone 3GS, iPhone 4, second and third generation iPod touch (late 2009 models with 32GB or 64GB). Some features may not be available on all products. For example, Multitasking requires iPhone 3GS, iPhone 4 or third generation iPod touch (late 2009 models with 32GB or 64GB).