From the Desktop: It's a Users' World - page 3
So let's back up for a second and examine this question: of all of the Linux distributions out there, which environment is loaded by default most? I think it has to be KDE, though I will readily admit this is just a feel, not actual numbers. KDE is the default in Slackware and (the distro custom made for newcomers) Corel Linux, just to name a few. Red Hat seems to be the only big purveyor of Gnome right now, which means that any new Linux users are likely going to see KDE first. Borrowing from Newton's first law of motion, a user at rest will stay at rest, and KDE will be the more-used environment. For now.
I'd rather Linux be on the winning side of that argument any day of the week.