Google co-founder Sergey Brin announced today that Google will be accepting pre-orders for a very early "Explorer Edition" of its Project Glass.

U.S-based attendees at Google's I/O developer conference will be able to pre-order the glasses for $1,500. They will ship early next year. At this point, there is no online ordering available; only conference attendees. Orders are also limited to those in the U.S. due to regulatory issues, Brin said.

Brin made a surprise appearance at I/O for a high-flying demo of Project Glass.

Utilizing Google+ Hangouts, Brin flashed to several people in a blimp high atop the Moscone Center in San Francisco. All were equipped with the Project Glass glasses, and they proceeded to jump from the blimp, sky dive over San Francisco, and land on the roof of the city's convention center.

Bikers, also equipped with Project Glass, then hopped on several bikes and performed a number of stunts before passing the glasses to a man who rappelled down the side of Moscone Center. That man passed it back to the bikers, who rushed into the main hall.

Google first tipped Project Glass in April. The glasses let you get texts, emails, music, weather, and more beamed directly to your field of vision. The concept device puts your smartphone into a pair of slim glasses and projects its contents for some futuristic, voice-activated fun.

Google Glass designers today gave an overview of the idea behind Glass. In designing the product for the last 2.5 years, Google wanted a device that was "close to your senses while not blocking them," one of the designers said, prompting the search giant to position Glass above your eye, not in front of it.

"If this is not ridiculously light, it does not belong on your face," she said. Google does not want to compete with a user's individuality. As a result, the latest prototype weighs less on your nose than the average pair of sunglasses.

Google did not reveal specific specs for Project Glass, but the designer said it includes a camera and a button on the top for taking photos, a "pretty powerful" processor, a "lot of memory," a touch pad on the side, microphones, speakers, multiple radios, as well as sensors like gyroscopes, accelerometers, and a compass.

Ideally, Project Glass will one day allow users to instantaneously access data. It should be "so fast that you feel you know it," without having to conduct a search, one designer said, though he acknowledged that's likely not something that will happen in the near future.

The effort, which is still in the planning stages, comes from Google X, a secret lab of future products first unveiled in November.

Brin first showed off Project Glass last month on the Current network talk show hosted by Gavin Newsom.

Google today also unveiled Android 4.1 Jelly Bean as well as its Nexus 7 tablet from Asus and the Nexus Q streaming media player.