This is great news. Dell has officially started selling computers that come with the Ubuntu Linux distribution instead of Microsoft Windows.
I think this a compelling development for three reasons:
First, it adds additional credibility to the notion that Linux in general, and Ubuntu specifically, is an on-par replacement for Windows. I can personally attest to that notion, since Ubuntu has been my primary platform at work for over a year, but the force of Dell behind that notion is a lot more significant than some random blogger.
Second, it means better support for the Dell hardware within Ubuntu specifically and Linux generally. For the non-geek, there are special pieces of software called "drivers" that let the operating system (and thus, all the other running programs) interact with the computer hardware. For instance, when a program wants to make a sound, it "talks" to the sound driver which, in turn, "talks" to the physical hardware that your speakers plug in to. It's less and less common these days, but there are still isolated cases where Linux drivers for certain pieces of hardware are buggy, non-existent, or not full-featured. With Dell selling the machines, it's a pretty much sure bet that any of the hardware they include will be fully supported.
Third, for anyone that's ever wanted to buy a new computer but did't want to buy "yet another copy of Windows," because you already have a copy of Windows on the old computer that you're never going to use anymore, you can now buy the less expensive "Ubuntu-version" of the Dell computer and just re-install the copy of Windows you already have. This lets people that don't need another copy of Windows get around the so-called "Windows Tax". How much will you save if you go with the "Ubuntu-version" over the "Windows-version"? A guy by the name of Nat Tuck has already run the numbers. It looks to be a savings of about 10%.
Oh, and by the way, even if you didn't know it, you already are a Linux user. :-)