UPDATE: FCC documents posted on Monday reveal specs of Google's Nexus One phone - Faster web access, supports both AT&T and T-Mobile 3G data. Read More.

A photo of the Google phone, or the Nexus One - which Google employees are currently testing out and will go on sale in January - has been released on Twitter.

The image (above) was posted on Saturday on Twitter by Cory O'Brien, an account manager at a San Francisco Bay Area marketing agency that does not list Google as a client.

O'Brien tweeted Google Phone = iPhone + a little extra screen and a scroll wheel. Great touch screen, and Android.

The Nexus One, according to the Wall Street Journal, is manufactured by HTC Corp. and runs on Android, Google's operating system for mobile phones.

The phone will be sold online by Google and according to Wired, it will be unlocked, allowing Google to have more control over the hardware and software without having too much network carrier interference.

On Saturday, Google posted a message on its Mobile Blog referring ambiguously to a new mobile phone 'concept' device that Google's employees had been given to test.

This new device, called Nexus One, combines innovative hardware from a partner with software that runs on Android to experiment with new mobile features and capabilities, Mario Queiroz, a Google vice president of product management wrote in the post.

The difference between this Android phone and others already out there in the market, is that Google designed the entire software experience behind the phone, the source said. This includes the applications that run on the phone to the look and feel of each screen.

According to TechCrunch, the device looks to be coming out in January.

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