Designing a New Version Control System?

tekvov asks: "When Linus Torvalds decided to use BitKeeper as the version control system for Linux there seemed to be a lot of controversy and many challenges to create a better system than CVS. My question is exactly what would this 'better system' look like? How is the subversion project, Tigris, doing at creating a new version control system? Basically, does the Open Source Community need new tools in this aspect of development? And if so, how should these new tools look?"