Jaan Tallinn is one of the programmers behind Kazaa and a founding engineer of Skype. He is also a partner in Ambient Sound Investments as well as a member of the Estonian President’s Academic Advisory Board. He describes himself as singularitarian / hacker / investor / physicist (in that order).
He is considered to be one of the foremost experts on P2P technologies, and together with Ahti and Priit worked out the core elements for Kazaa and Skype. He continues to be involved with Skype, where he’s one of the lead system architects.
In recent years Jaan has found himself closely following and occasionally supporting the work that SIAI and FHI are doing. He agrees with Kurzweil in that the topic of Singularity can be extremely counterintuitive to general public, and has tried to address this problem in a few public presentations at various venues.