Another interesting comparison is git and GitHub. We invented a new technology to replace CVS/Subversion/SourceSafe/$CENTRALISED_VCS, and it really does exist,

Another interesting comparison is git and GitHub. We invented a new technology to replace CVS/Subversion/SourceSafe/$CENTRALISED_VCS, and it really does exist, and it's better than all of those old systems partly because it really is decentralised, and it's also based on crypto(graphic) primitives, but 99% of the people who think they've bought into it are actually just using another centralised service all over again. Or to put it another way - when GitHub goes down a disturbingly high proportion of a) git users are unable to get any work done at all, and b) build systems just break. (Ok, git didn't invent the DVCS. But it was better enough on a number of important axes than those that came before it - including "being used by a high-profile project" - that you can say that it made DVCSs happen.)