After more than a year of speculation about a “GPhone,” the Google-powered G1 phone was unveiled today in New York. As we reported last month, this will be a T-Mobile phone (built by HTC), and it will be available to T-Mobile subscribers for $179 starting Oct. 22 (two-year contract).

It features a touch screen that slides up to reveal a full QWERTY keyboard. It also has a 3-megapixel camera, on par with that of the iPhone, and it will bundle a suite of native Google applications, including Street View‘s first appearance on a mobile device.

The price slightly undercuts that of the iPhone, and it will have a more “open” development platform (presumably fewer filters than those imposed by the app store approval process). It also boasts faster download speeds than the iPhone, although T-Mobile’s 3G network is still under construction and currently limited to 16 U.S. markets.

This will follow closely behind the demand and appeal (and lowered price tag) that Apple has ignited in the mobile market. And judging by the video provided with the T-Mobile press release and another one provided by Google, it looks like a pretty sexy device. It’s going to need to be in order to compete with the iPhone. It could have a big impact, regardless, with T-Mobile subscribers who have been contractually motivated against iPhone purchases.

We’ll see lots more carrier deals formed in the coming months that will broaden the market for next generation phones. Mobile local search (both app development and adoption) will get a big boost from all this, as we keep saying. Carriers have finally been forced to open their doors, and there is no going back now.