Caldera, Conectiva, SuSE and Turbolinux are going to consolidate their offerings into a single "United Linux" distribution. This is a good thing. Each company will retain it's geographical stronghold (US, South America, Europe and Asia), but collaborate on a single distribution.
Had this happened in the 80's during the UNIX wars, things might be a little different today.
The cause? To address RedHat's de facto dominance. It's not the end of multiple distributions, RedHat and Debian will still exist; Sun is still coming out with it's own distribution that promises better integration with Solaris. This isn't going to stop Joe's Garage Linux from playing around with some interesting idea in distribution or system management.
Yet another example of TMTOWTDI: there are lots of ways to do something, but they're not all uniformly good. :-)