Everything you need to know about iPhone 4

Steve Jobs announced iPhone 4 at the Worldwide Developers Conference today, calling it the biggest leap since the original iPhone. At 9mm thick, it's 24% thinner than the iPhone 3GS (but weighs 3 grams more), it has a front-facing camera (VGA resolution) with "FaceTime" video calling (but it's Wi-Fi only), an LED flash alongside its new 5-megapixel camera's lens on the back, and separate buttons for volume up, down and mute. It also has a stainless steel rim that functions as the antenna.

Its 3.5-inch display, the same size as current iPhones, has higher resolution (960 x 640 pixels), with four times the pixel count of its predecessor. Jobs is calling it the "retina display." That's because, as Jobs put it, "There's a magic number around 300dpi, if you hold something about 10 to 12 inches away from your eye, it's the limit of the human retina to distinguish pixels." The kicker? IPhone 4 has 326dpi resolution.

iPhone 4 has a larger battery than previous models, and Jobs says that will give it 40% more talk time, six hours of 3G browsing, 10 hours of Wi-Fi browsing, 10 hours of video, 40 hours of music, and 300 hours of standby. Those numbers have been exaggerated in the past, so your mileage will probably vary.

This new version of the iPhone has improved video-shooting capabilities as well. It's now packing a 720p camcorder that shoots at 30 frames per second. There's also a new video-editing app for $4.99 — a mini version of iMovie developed specifically for the iPhone.

Jobs next demonstrated the previously announced operating system update for the iPhone, now renamed "iOS 4". It'll be available as a free upgrade for iPhone 3GS, iPhone 3G (not all features supported) and iPod Touch (no 1st-gen) users June 21st. Its claim to fame? Multitasking, and even though Apple is late to the multitasking game for cellphones, Jobs says his company's figured out how to accomplish this without running down the battery.

Finally, pricing: It's the same as the iPhone 3GS is now. The 16GB iPhone 4 will sell for $199, and the 32GB for $299. And hey, AT&T won't rip you off this time if you're upgrading early, giving you the subsidized price, plus $18, if you bought an iPhone last year. It'll be available in black or white on June 24th, with pre-orders starting next week, on Tuesday, June 15th.

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