Google has unveiled its highly anticipated "Google Phone," or the Nexus One, an Android-powered smartphone and the first device the company will sell directly from a new online store.

At a Google press event held Tuesday afternoon at the company's Mountain View, Calif. headquarters, Google vice president Mario Queiroz billed the new Nexus One as a "superphone" and an "exemplar of what's possible" on mobile phones running Android. He didn't precisely define the term superphone, other than to suggest it has greater capabilities than today's existing smartphones.

Queiroz spoke along with several other panelists including mobile guru Andy Rubin, HTC CEO Peter Chou, and even competitor Motorola Co-CEO Sanjay Jha. All of them took pains to deflect concerns that Google has shifted course with its Android OS, or that Google could muddy the waters for its current wireless industry partners by selling its own branded device.

The hardware itself looks pretty slick, even if the moniker "superphone" ends up in the eye of the beholder. Essentially, the Nexus One is a slim touch-screen slab handset manufactured by HTC, the company behind the original , the , and the . The Nexus One weighs 4.6 ounces and measures 0.45-inches thick. It features a 3.7-inch, 480-by-800-pixel glass capacitive AMOLED touch screen, a next-generation 1-GHz Qualcomm Snapdragon CPU, and Android 2.1, a brand new version of the company's open-source mobile OS.

Other hardware features include a 5-megapixel auto-focus camera with an LED flash and geotagging capability, 512MB of internal memory, and a microSD card slot. Two mics provide Bluetooth headset-like active noise cancellation for improved call quality in loud environments. The trackball doubles as a notification tool, Queiroz said, in that it contains a multi-color LED for indicating incoming calls and other notifications. A 3.5-mm headphone jack and stereo Bluetooth support offer music lovers multiple options for listening to tunes.

Queiroz reiterated Android's virtues during the course of the press conference. "Android enables lower manufacturing costs and faster time to market," he said, in a direct shot at Microsoft before turning his sights on Apple, whose can't run multiple applications simultaneously except in specific narrow circumstances.

"The [Android] architecture enables true 'always on' applications in the background. I can be listening to music, playing my favorite game, my wife can call me, I'll pick up the phone, talk to her, hang up the call, and continue listening to music and playing my game  much like what you have on your desktop computer or on your laptop," Queiroz said. The 1-GHz Snapdragon CPU helps matters, of course, and should be beefy enough for running several applications at once; some earlier Android devices have been sluggish in this regard.

Android 2.1 sports a number of improvements, including smoother menu animation, five new home screen panels, and a funky new Weather widget that offers an interactive graph for real-time weather data. Eric Tseng, product manager at Google, demonstrated live wallpaper of a lake that responded to touches by showing ripples in the surface of the water.

The photo app, meanwhile, offers new 3D visualizations, a stacks-of-photos idiom for interacting with albums, and faster photo loading. The device syncs with Picasa albums in the background, and uploads videos to YouTube with a single click. Finally, every text entry box is now voice-recognition-enabled with server-side processing, not just from within Google Maps Navigation like in Android 2.0.

Tseng also showed off a sneak preview of Google Earth for Android, complete with 3D-enhanced flyover views. The animation was a little choppy here, but undeniably impressive for a cell phone. The Nexus One doesn't support modem tethering, though Google mobile guru Andy Rubin said at the conference that it's just a technical issue, not a strategic one at this point.

Android 2.1 will come preloaded on the Nexus One, and will be available "in a few days" to the open-source community. But carriers and hardware vendors will have to approve individual updates for existing Android handsets.

As indicated, the Google Nexus One will sell for $529.99 unlocked, or $179.99 with one of T-Mobile's two-year service plans. The unlocked version will work with an AT&T SIM, but only at 2G speeds, as it lacks support for the requisite bands to access AT&T's 3G network. In a first, Google will sell both unlocked and contracted versions of the Nexus One through a new online portal located at www.google.com/phone beginning today. Buyers can also order custom engraving with the phone.

Separately, Google has also announced Verizon and Vodafone as partners, indicating that a CDMA version of the Nexus One will be available in the spring. For now, customers can buy a Motorola Droid on Verizon from the new Google online store.

One telling comment came later in the conference from HTC CEO Peter Chou, who described the Nexus One as just the beginning of what is possible with Google's new . In a response to a reporter's question about how Google plans to avoid AT&T's trouble in providing enough coverage for its iPhone customers, Chou emphasized the distinction between carrier service offerings and the phone itself.

"I believe an operator has their own offering to their customers," Chou said. "This [online store] is one of the additional channels for people to have different choices, and also this is one way that we can get some of our innovation out a little bit earlier"perhaps a veiled reference to lengthy U.S. carrier device approval processes and exclusive deals, which often frustrate handset vendors and consumers alike.

Later, Motorola Co-CEO Sanjay Jha deflected concerns about the Nexus One's potential impact on Motorola Droid sales, and made several good-natured comments about his rival at HTC. "I think Nexus One is a good phone. I think Droid is a good phone. I think we will update Droid to the newest [Android 2.1] software. [HTC CEO] Peter and I compete, but both of us support the [Android] ecosystem. I think today Android is the fastest growing ecosystem. I think that is ultimately good for all of us participating."