While Twitter co-founder Biz Stone’s new startup Jelly has been light on the specifics (what the hell is it, really?), it has been heavy on snatching talent as of late.

According to All Things D, we can now say hello to Jelly’s new Chief Operating Officer – and it’s Twitter’s Kevin Thau.

Thau’s most recent project at Twitter was the newly-launched Twitter Music, the company’s new standalone music discovery app that was built out of the acquisition of We Are Hunted. But Thau has been at Twitter much longer than the beginning of that project, once managing Twitter’s mobile engineering and design teams. After that, Thau became VP of Business Development.

Earlier this week, Biz Stone came out and announced the identity of his Jelly co-founder and CTO. It’s Ben FInkel, who once served as the New Users Experience manager on Twitter’s Growth Team. Another former Twitter employee, Vítor Lourenço, left Twitter and is now consulting the folks over at Jelly. With today’s news that Thau is leaving Twitter to work on Jelly, that makes three high-profile poaches by Biz Stone and his new startup.

But once again, what is Jelly? Details are scarce, but we know that it will be a mobile-focused, free service of some kind.

“News of Jelly emerged unexpectedly early so I’ll wait a bit to share more about the team. In the meantime, I’ll say this. Jelly will be for everybody, it will be developed first and foremost for mobile devices, and it will be free. But, it won’t be ready for a while,” said Stone, when announcing the startup.