Yo, the simple app that just sends a “yo” to your friends, has closed $1.5 million in seed funding with a $10 million valuation and is finally ready to talk about its investors. They include Betaworks, Mashable’s Pete Cashmore, and the founders of China’s Tencent, among others.

Yo previously confirmed it had raised $1.2 million in funding, but until today it was unwilling to disclose who had invested in the company. We did know co-founder and Mobli CEO Moshe Hogeg had given some of his own money to the project, but we knew it wasn’t all $1.2 million of it. Business Insider reports that the founders of Tencent were also in the round.

CEO Or Arbel tells us he’d been in funding discussions with Betaworks since May but couldn’t divulge this information until now. This latest tranche added another $300K to the total, closing the round at a total of $1.5 million. A source tells us the round was raised at a $10 million valuation.

The company will use the funds to expand operations in San Francisco, says Arbel, who moved Yo’s headquarters out of the Airbnb offices it had been occupying and into The Hatchery in San Francisco’s SOMA district.

Yo has already started hiring a team of engineers and business development folks to help the company expand brand partnerships. These partnerships could mirror what Yo was able to do with updates to users every time a goal was scored at this last World Cup or inform a user that their flight has arrived on their preferred airline.

To date, Yo has had over 2 million installs of the app and currently has over 2,000 developers who have started working with the API.

“The value of this round goes far beyond the dollar amount that we received,” said Arbel in the official announcement. “Bringing such incredibly smart, talented, and experienced people into the Yo team at this stage is an incredible advantage that will allow us to accelerate the growth and provide more and better value to our users.”

Some may scratch their heads at why anyone would give such a basic app that kind of cash.

“We are fascinated by these uses of simple yes/no, on/off communications tools,” Betaworks co-founder John Borthwick wrote on the Betaworks blog. “As the notification layer becomes the primary interface of alert-based information on your phone — as the OS’s allow navigation and controls in those alerts — there will emerge a new class of applications that mediate this layer for web sites, other app’s and connected hardware.”