Today, online search and advertising giant Google will officially announce its long-anticipated and oft-rumored gPhone smart phone platform, according to numerous sources. The platform (code-named Android) consists of an open mobile phone platform and associated Google software and services.

Several wireless carriers around the world have reportedly signed on to sell phones based on the new platform, but Google has spent much of last weekend finalizing other carrier deals. More than 30 companies, such as HTC, Intel, Motorola, Samsung, and Sprint are involved in what's being called the Open Handset Alliance, the name given to Google's phone initiative.

Google has refused to discuss its phone plans publicly thus far, but in recent days, many details have slipped out, and the company will allegedly announce the project at 11:00 A.M. Eastern today. Android was previously the name of a company run by long-time Silicon Valley innovator Andy Rubin. Google bought the company in 2005, and Rubin now heads up Google's phone efforts.

With the understanding that nothing is written in stone until Google makes the official announcement, here's what's expected of the gPhone: Google's phone platform will be based on Linux and will be provided to developers for free in an effort to lower costs in the mobile space and jumpstart mobile application development. As with Google's Web-based services, the company expects to make most of its money in the mobile space via advertising, although it's unclear what form the advertisements will take.

Google-powered phones aren't expected to hit the market until mid-2008. Although the initial generation of devices will most likely be marketed by a variety of third-party vendors, Google will probably sell a Google-branded phone of its own at some point as well.

The potential market, of course, is humongous. Today, there are more than one billion cell phones in use worldwide, and more than 10 percent of those are smart phones. Smart phone usage is expected to triple by 2011, however, to reach more than 310 million customers. By that time, mobile phone advertising is expected to approach $5 billion annually, up from a predicted $106 million this year.