>> Dow 21,000 by 2010
>
> Pardon my ignorance, but can anyone explain to me in PLAIN
> English what the numerology behind stock market report means?
> 21,000 of what?
Short answer: Index points :-) Longer answer: the DJIA (and in general, other averages) is a weighted average of the prices of the index constituents.
Here's a detailed answer: http://money.howstuffworks.com/question44.htm