Ubuntu as the end to factionalismUbuntu is making significant progress where other distributions have failed for ten years: namely, consolidating the resources of the free-software community into a single Linux distribution that has enough users and developers to present itself to those outside the IT world as the preeminent representative of the Linux community.
A plurality of distributions is great for innovation and ensuring that every user can find a Linux to fit her needs. But at a certain point, after a certain amount of time, the Linux community--or at least a substantial portion of it--needs to move past factionalism in order to support a single, standardized distribution that can meet the needs of most desktop users.
It's difficult for Joe the Plumber to install Linux on his desktop when it takes hours of googling in order to figure out what all the different components of a Linux system are (Ubuntu or Fedora or SUSE? Gnome or KDE?), and which ones are best for a given situation. It's also easier to develop applications for desktop Linux when its components are standardized by a single distribution.
Ubuntu has managed to make itself almost synonymous with Linux (proof: google 'linux' and ubuntu.com is the second result, above linux.com and the Wikipedia article), at least for non-techies. Sure, there are problems with this association, which grossly oversimplifies the relationship between the kernel, desktop environments and applications. But simplification--even if it approaches benevolent deception--is what Linux needs if it aspires to take over the desktops of the world.
Ubuntu's dominance doesn't mean that other distributions can't exist or should become irrelevant. But there needs to be one distribution that mainstream users can directly and easily associate with Linux, without having to learn what a kernel is or read the 26-year history of the GNU project. And Ubuntu may well prove to be that distribution.