While most of the important Interner software is open source, this "vir- tuous cycle" extends both ways. Open source development has been enabled from the beginning by the cooperative technologies of the Internet. Initially, developers at Berkeley used the Betkeley campus TCPIlP network to build and the new Internet to distribute BSD. Later, Usenet was used to support collaborative development of GNU tools and put developers in touch with Linus Torvalds through the comp os minix newsgroup. Today, the Internet supports collaborative development such as CVS, continuous update of packages using tools such as Debian apt-get, social software such as Slashdor, and collaborative instruments like SourceForge. The economist Bradford DeLong lias a framework for the economic analysis of technological revolutions. The four key questions to monitor for a revolution are: