Google Jan. 5 formally unveiled the Nexus One smartphone, demonstrating many of its features during a press event and opening a Web store to sell the device unlocked to consumers who wish to purchase it online for $529, or $179 with a two-year contract from T-Mobile.

For a look at the Google Nexus One smartphone, click here.

Today, consumers in the United States, United Kingdom, Hong Kong and Singapore can buy the Nexus One without service, which means any GSM network SIM (Subscriber Identity Module) card can be inserted into the device, or purchase the phone with service from one of Google's operator partners via Google's new hosted Web store.

Verizon Wireless in the United States and Vodafone in Europe will join T-Mobile in selling the device in spring 2010, said Mario Queiroz, Google's vice president of product management, during the Nexus One launch at the company's Mountain View, Calif., headquarters. Google this year will add more wireless partners and in the future will sell additional smartphones through its store to tempt users, he said.

This is a significant development, broadening the reach of the smartphone many reviewers are claiming most closelyapproximates the satisfying experience of Apple's popular iPhone.  

Customers must get the iPhone from AT&T Wireless, but Google's approach with the Nexus One emphasizes choice, specifically users' ability to pick a wireless carrier, where and when Google and its partners can accommodate users.

While the device is unlocked, it has limitations; it won't work with the frequency band used by the AT&T and Rogers networks for 3G data and is incompatible with CDMA (Code Division Multiple Access) networks such as Verizon and Sprint.

While Google said it is working to bring Nexus One phones to the Verizon network, this will not include a GSM device, so it will not be compatible with T-Mobile, AT&T or other GSM networks.

Contrary to previous reports, Google Android Vice President of Engineering Andy Rubin said during the event that HTC built the phone entirely without every little software detail being dictated by Google.

In essence, this is another Google Android phone, just one that happens to be a little closer to Google's ideal of what a Web-enabled phone should be than the Motorola Droid or other Android phones.