Actually that's not true. Qwerty is a very bad layout for keyboards. The guy who invented it was named Qwerty. It was originally designed for typewriters and to be difficult to use to force the typist to slow down to reduce mistakes. Many alternate layouts have been proposed over the years but Qwerty became the defacto standard because it was so widely used by businesses with typewriters. That's what people learned and we've been stuck with it ever sense.

The fact that you can spell 'typewriter' with only keys from the top row might have something to do with the early popularity of that arrangement...

Of course everyone in the know prefers 'DHIATENSOR'.

Wikipedia partially disagrees: http://en.wikipedia.org/wiki/Qwerty

It slows you down to prevent jams. The guy's name was Sholes.

Actually, it's not supposed to slow you down. It's supposed to make sure you're normally hitting keys that are far apart, which means the hammers won't interfere with each other. QWERTY is a pretty good layout because of it. The next letter you try to type is rarely in the domain of the finger that just pressed down, meaning you can line up a number of keys to be pushed at once.

In the Design of Everyday Things, Donald Norman talks about keyboard design a lot. QWERTY is really good, so switching to layouts that are only slightly better (dvorak) end up not being worth the time and effort.