Google's long awaited Nexus One phone has been launched and will be available in the UK, initially through Vodafone.
The search giant's own branded mobile phone will also become available from Verizon Wireless in the US with other carriers expected to be announced shortly.
HTC made the phone, which has a 3.7-inch OLED display and runs a 1 GHz Snapdragon processor. It's 11.5 mm thick.
The trackball pulses light to alert users of events like new mails or text messages. The phone has light and proximity sensors, in addition to a compass and accelerometer. The light sensor will automatically dim the display when a bright light isn't necessary. The proximity sensor also dims the display light when a user moves the phone to the ear to talk. The 5-megapixal camera includes an LED flash and takes MPEG 4 videos.
The phone also has two microphones, one in front and one in back, enabling noise cancellation. That means when users are in a noisy environment, the background noise is cancelled out.
In the demonstration during a webcast press event, the phone response seemed zippier than that of the Motorola Droid, perhaps due to the fast Snapdragon processor and upgraded software.
The software, Android version 2.1, builds on Android 2.0, currently in the Droid phone. It has more customisation capabilities. For example, users can place widgets across five home screens instead of three.
The Nexus One also introduces the concept of live wallpaper. The background images, which sit behind widgets, are animated. In an example, a photo of a small lake with a reflection shows leaves floating in the water. Touching it shows ripples on the water.
Android 2.1 voice enables every text field in the device. That means users can speak Twitter messages, Facebook posts and e-mail messages and the phone will convert them to text to send.
"One question we asked ourselves some time ago was what if we work even more closely with our partners to bring devices to market which are going to help us showcase quickly the great software technology we're working on here at Google," Mario Queiroz, vice president of product management at Google said. "We've done just that."
He called the Nexus One an exemplar of what's possible on mobile phones through Android and said the name, meaning point of convergence, is "where the web meets the phone."
The most recent rumours of a phone that would be sold direct by Google surfaced last year, after employees began posting messages online about receiving the phones. At the time, Google said that it had indeed handed out phones to some employees but the company said the devices were experimental, meant to let workers test new features. Then, in December, the Wall Street Journal reported that the rumours were true and the Nexus was to be launched shortly.
Google first announced Android in 2007 saying that it wanted to offer the industry a unifying mobile platform. It had complained about having to recreate mobile applications to work on each of the many wireless operating systems. Google said that Android - which ironically added yet another platform to the mix - could help solve that problem.
While Android got off to a relatively slow start, with just one phone model on the market for about a year, it has recently shown signs of posing a threat to Apple's iPhone dominance. There are now more than a dozen models of Android phones available.
On Monday, a ChangeWave survey showed that 21 percent of respondents who plan to buy a smartphone in the next three months prefer Android. That compares to 28 percent who want an iPhone - four percent fewer then when ChangeWave asked in September.