Steve Jobs has introduced the next-generation iPhone, prosaically known as the iPhone 4. This wasn't unexpected, but the Apple chief did reveal a number of features not mentioned in pre-release leaks.

Jobs unveiled the handset at the company's Worldwide Developer Conference in San Francisco, and since the man won't actually let us in to such events, we have gleaned the news from several live blogs, including Ars Technica's.

There had been some commentary that the much-discussed Gizmodophone might not be a final release of Apple's new handset due to the fact that it had visible gaps in its case. Well, it turns out that those gaps are separations of the phone's two-element antenna, which comprise the case — one side of the phone is the antenna for Bluetooth, Wi-Fi, and GPS, the other is UMTS and GSM.

Also undiscovered was that there's a new motion sensor in the new phone: a three-axis gyroscope. According to Jobs — and visible in his demo — the gyroscope adds a far greater degree of motion-sensing capabilities, including pitch, roll, and yaw, plus rotation about gravity. The gyro is supported by new CoreMotion APIs.

Although the new front- and rear-facing cameras were known from leaks, there were some new details. Namely, that the rear camera is a five-megapixel unit, but — helpful for image quality — Jobs said that the image-capturing elements in the new camera are of the same size as they were in the iPhone 3GS's three-megapixel camera: 1.75 μm.

The camera also has a backside-illuminated sensor to help with low-light imagining, captures 720p HD video at 30fps, has a 5X digital zoom, and an LED flash that can be kept lit during video capture — although Jobs made no mention of how that type of usage might drain battery life. Jobs also announced a new iMovie app for the iPhone.

Speaking of battery life, Jobs said that due to the power-miserliness of the new iPhone's A4 processor plus its larger battery, the new phone has 40 per cent more talk time on 3G (up from five to seven hours), and can handle six hours of 3G browsing, ten hours of Wi-Fi browsing, and 300 standby hours.

The front-facing camera can be used, as expected, for video chats, but only over Wi-Fi. As Jobs told his crowd: "It's going to be Wi-Fi only in 2010. We need to work a little bit with the carriers..."

The iPhone 4's display density is a bit better than those intrepid Czech microscope wielders discovered last week: 326 pixels per inch. Apple dubs the new display the "Retina Display," citing stats that say the human retina can discern only 300ppi at a distance of 10 to 12 inches. Jobs noted that the iPhone 4 has 78 per cent on the iPad's pixels "in the palm of your hand."

The iPhone 4 is also noticeably thinner than the iPhone 3SG — 9.3mm, 24 per cent thinner than the 12.3 mm of the iPhone 3GS — and will be available in white and black. Both the front and back of the phone are glass, which Jobs touted as being 30 times harder than plastic.

The new phone will run $199 for a 16GB model and $299 for a 32GB version, and it will go on sale on June 24 in the United States, France, Germany, Japan, and the UK, with pre-orders being taken beginning June 15. The iPhone 3GS will remain available, with its price reduced to $99.

Finally, Jobs reassured his US customers: "AT&T is going to make an incredibly generous upgrade offer. If your contract expires at any time in 2010, you can upgrade to the iPhone 4. You can get it up to six months early." ®