Well, this is pretty interesting:
GNU Free Call is a new project to develop and deploy secure self-organized communication services worldwide for private use and for public administration. We use the open standard SIP protocol and GNU SIP Witch to create secured peer-to-peer mesh calling networks, and we welcome all participation in our effort.
Our goal is to make GNU Free Call ubiquitous in a manner and level of usability similar to Skype, that is, usable on all platforms, and directly by the general public for all manner of secure communication between known and anonymous parties, but without requiring a central service provider to register with, without using insecure source secret binary protocols that may have back-doors, and without having network control points of any kind that can be exploited or abused by external parties. By doing so as a self organizing meshed calling network, we further eliminate potential service control points such as through explicit routing peers even if networks are isolated in civil emergencies.
More (quite a bit more, actually!) on the official announcement page.
Christopher Boyd (Thanks Alex)