We may not really know what it is yet, but Twitter co-founder Biz Stone’s new startup is accumulating talent at a pretty fast clip.

Today, Stone announced that Loren Brichter, former Apple engineer who worked on the original iPhone and founder of the popular iOS game Letterpress, had joined the company’s Executive Advisory Board. He’s the first member of the board. Brichter also worked with Twitter, and is responsible for their pull-to-refresh “user interface mechanics” patent.

“Even if you work with some of the best people in the world across several fields of expertise, there will always be more brilliant people outside your company than inside. Jelly has started assembling an external pool of skill to help us build a world-class product,” says Stone. “We are proud and lucky to have Loren as part of our extended team—he will make us better at our own work. More importantly, Loren’s participation means that Jelly will be a finer product in general. That’s just good for everyone.”

Jelly has been on a hiring kick as of late:

About a week ago, Biz Stone announced that Facebook COO Sheryl Sandberg’s former assistant, Camille Hart had joined the team as the Chief of Staff.

In the past couple of months – former Twitter employee Ben Finkel (co-founder and CTO), Twitter’s Kevin Thau (COO), and employee #1, designer Austin Sarner.

And a few weeks ago, Stone revealed some of his early investors. That list included Twitter co-founder Jack Dorsey, Al Gore, and Bono.

Stone is keeping a tight lid on Jelly. All we really know is that it will be a free, mobile-focused service. Here are some of my guesses and dot connections following the investor disclosure:

“We chose angels like Al Gore, a Partner at KPCB and Chairman and Co-founder of Generation Investment Management, Greg Yaitanes, a Hollywood director, and Roya Mahboob, an entrepreneur doing amazing work for women in Afghanistan partly because they work in divergent fields. Knowledge diversity is something we prize highly and is also something that will be represented in our product,” said Stone.

When Jelly was first officially announced, Stone said this:

“People are basically good – when provided a tool that helps them do good in the world, they prove it. Jelly is a new company and product named after the jellyfish. We are inspired by this particular animal because neurologically, its brain is more “we” than “me.” Also, for the past 700 million years, this decentralized structure has been wildly successful.”

“Help them do good in the world.” Is that the key phrase here? Is Jelly some sort of mobile social good app? Who knows, I guess we’ll just have to wait and see, as Stone is quite serious about keeping a tight lid on this thing. But the addition of Bono, Al Gore, and an Afghani activist hints that Jelly will be striving to do some sort of international good at the very least.

Whatever it is, Stone says that it won’t be ready for quite some time.