Apple CEO Steve Jobs on Monday announced the fourth-generation iPhone during a keynote speech at the Worldwide Developers Conference in San Francisco.

Jobs described the phone as, “beyond a doubt, the most precise thing and one of the most beautiful things we’ve ever made” before highlighting a number of its new features.

The iPhone 4 will ship on June 24, with pre-shipment orders starting on June 15. The iPhone 4 will ship initially in the US, France, Germany, the UK and Japan. By the end of September, it will be available in 88 countries.

Updated design

Apple says the iPhone 4 is 9.3mm thick, or 24 percent thinner than the iPhone 3GS. It includes new camera with an LED flash on the black, but a second, front-facing camera as well. There are new volume buttons, a mute button, plus a second microphone on the top for noise cancellation. Just like the iPad, it now incorporates a micro-SIM tray.

Apple has also engineered three integrated antennas into the design: one for Bluetooth, one for WiFi and GPS, and one for UMTS and GSM.

Improved display

A new screen technology called a retina display add much higher precision to the iPhone. In fact, at 326 pixels per inch, it’s double the 163 pixels per inch resolution of the iPhone 3GS.

The new display is the same 3.5 inches diagonally, but at 960 by 640 it has four times as many pixels as the previous model. And the 800:1 contrast ratio is also four times that of the iPhone 3GS. It uses the same IPS display technology as the iPad and the iMac for good color fidelity, brightness, and viewing angle.

New processor

Designed by Apple, the A4 chip is tiny and has good power management. Apple went with the micro-SIM design to save space, mostly for a new battery that, coupled with the new chip, Apple says provides 40 percent more talk time. The company says talk time is up from 5 hours to 7 hours; 6 hours of 3G browsing; 10 hours of WiFi browsing; 10 hours of video; 40 hours of music; and 300 hours of standby.

Environmentally, the new iPhone is arsenic free, BFR-free mercury-free, PVC-free, and made from highly recyclable materials.