Updated A Tuesday press-conference invitation and a T-Mobile leak make it ninety-nine per cent certain that Google will announce its Android-based Googlephone Nexus One smartphone at 10:00 a.m. on Tuesday, January 5, at its Mountain View Googleplex.

This morning, a carefully selected slice of the tech press received a short but sweet invitation to the announcement event. In the long-standing tradition of milking product announcements for every drop of suspense, the invitation doesn't mention the Nexus One specifically, but merely reads:

With the launch of the first Android-powered device just over a year ago, we’ve seen how a powerful, open platform can spur mobile product innovation. And this is just the beginning of what’s possible.

What seals the Nexus One deal is a T-Mobile intranet posting obtained by TmoNews entitled "Google Android Phone" that straightforwardly states:

Google, with support from T-Mobile, is scheduled to launch a new Android device in early January. The Google Android phone will be sold solely by Google via the Web.

• Support for this device including troubleshooting and exchanges will be managed by Google and HTC.
• T-Mobile will offer service support, including billing, coverage, features and rate plans.

Both of today's developments jibe with last week's tip that the Nexus One's coming-out party was going to be held on January 5.

You'll note that the T-Mobile intranet posting says that the phone will be "sold solely by Google via the Web" - T-Mobile is merely along for the ride as a service provider and monthly billing-meister. How well a software and services provider such as Google will handle hardware fulfillment as well as "support ... including troubleshooting and exchanges" remains to be seen.

Perhaps Google has a fulfillment and support partner that it will announce on January 5, as well.

After previously denying that it would be "making hardware" and that it wouldn't "compete with its customers" by offering its own phone, Google confirmed the existence of the Nexus One on December 12.

It can be argued, seeing as how the Nexus One is reportedly being manufactured by HTC, that Google was merely stretching but not snapping the truth when it denied that it was "making hardware."

We'll be interested, however, to see how it justifies its previous denials that it would not "compete with its customers" by launching its own phone. Perhaps Google's notion of "customer" is you and I, and not Android-phone developers such as Motorola, Acer, and HTC.

But Google's seeming duplicity isn't the central question for phone geeks. What they want to know is "How good is the Nexus One?" Well, at least one lucky HD camera–wielding geek with a poor understanding of depth-of-field is mightily impressed. He got his hands on a Nexus One running Android 2.1, and posted the following video review:

The answer appears to be that Google's Nexus One may shape up to be a formidable challenger to the current Cupertinian king of the smartphone hill.

Of course, there are small matters such as price, battery life, reliability, build quality, coverage, service, and support that are still unknowns. One certainty that we won't need to wait until January 5 for confirmation, however, is that sales projections are busily being reforecast at Palm. ®

Update

Late Tuesday in the US, Gizmodo reported that an unlocked and unsubsidized Nexus One will go for $530, or with an unsubsidized T-Mobile plan for $180 plus monthly service charges. More uncorroborated details are available here.