Open source is more than a way to get great software like web browsers Firefox and Chrome, word processor Open Office, art program GIMP and antivirus program ClamWin. It's a movement towards freedom of intellectual property - towards intellectual communism.
Open source software isn't new, though - the GNU Project, the precursor to Linux (a family of open source operating systems), was started in 1983. But in the past few years, open source has moved from a computer thing to a culture thing. Creative Commons took the idea of open source and applied it to intellectual property other than code.
Now some of the same principles - not being forced to pay for interesting things - are being brought back to the physical world through things like Decentralize Dance Paries. Which looks completely awesome.