Google announced a brand-new Google+ app for tablets today—but the presentation was quickly overshadowed by a jaw-dropping demo involving cofounder Sergey Brin and a couple of skydivers wearing Google Glasses.

Brin "interrupted" a speech being given by Google VP Vic Gundotra, coming on stage wearing a pair of the forthcoming Project Glass smart glasses. It quickly became clear that Brin was about to hold a live video "Hangout" on Google+ with a couple of Googlers who were flying over San Francisco in a plane.

After chatting for a few minutes, the Googlers skydived out of the plane, live streaming the jump through their Google Glasses to a raucous Google I/O crowd. Naturally, this was followed by some bicyclists performing crazy jumps and streaming their exploits through the futuristic glasses.

It turns out an "Explorer Edition" of the glasses is available for pre-order—but only to people attending the Google I/O conference. The glasses will cost $1,500 and ship early next year.

Brin stressed it is not yet a consumer device. This is for testers, to help Google make the product better.

"It's going to be something we'd like to get in hands of people who are really passionate about it," Brin said. It's going to be rough around the edges, so "you have to want to be on the bleeding edge, and that's what this is designed for."

After the skydiving and bicycling, video was shown of people using the Project Glass prototype while playing tennis, walking on the beach, or holding a baby, letting them easily capture pictures and videos of life events. The glasses have various sensors, including a compass and a gyroscope, and the latest prototype is lighter than "many sunglasses," Google officials said.

Other uses? You might be riding a bike and want to know how fast you're going. The glasses will tell you. Google asked developers to help them figure out what kinds of information users might want from Project Glass devices.

We still don't know when Google Glasses will hit the consumer market, but damn if the skydiving wasn't cool! You can watch the presentation yourself on the Google I/O site.

Right before the Glass demo, Google announced that Google+ is being liberated from the browser on tablets, with a new app hitting Android tablets today and coming to the iPad soon.

"We keep hearing the same request from users: 'when are we going to get a native tablet version of Google+?' Gundotra said. "The answer is you're going to get it today."

Google+ already has more users on mobile devices than desktops, Gundotra said. The tablet app is immersive, letting users scroll horizontally through friends and acquaintances' posts, which change in size depending on how much engagement each one receives. Photos, text, and videos each have a distinctive look, Gundotra said.

Google+ Hangouts, which provide live, multi-user video chats, will also come to tablets via the new app. Additionally, a new Google+ Events tool was unveiled.

An identical version of the new Google+ app is coming soon for the iPad, optimized for the Retina Display, and all the features hitting tablets will also come to Android smartphones.