Google is in the early testing stages of a new project that may aim to replace, or at least compete, with wikipedia. They've created a tool called 'knol', which stands for unit of knowledge. The idea is that a person can create a page about a certain topic. Others can add to or edit the page. The author may choose to place Google ads on the page.
Sound a bit like Wikipedia? There are a few key differences. First, a knol will have information about the author. Wikipedia allows complete and total anonymity.
Second, although others can add to or take away from the article, ultimately the author of the piece decides what stays and what goes. One person has control over the article. These two facts take away some of the complaints often raised about Wikipedia. That 'experts' aren't writing the the articles, and there is no oversight.
The third difference is that Wikipedia has never placed ads on their site. Users contribute and Wikipedia is a non-profit organization.
It's clear why Google would love to see the knol idea take off. Do a search for a noun on Google, any noun. Look at the first five listings. Chances are, Wikipedia is one of those links. I picked cat and Wikipedia was second. Just for fun, you should do a search for exploding coconuts, and click the I'm feeling lucky button.
Anyway, there are all of these people trying to find out about something, and they are being directed to wikipedia where they are not being hit over the heads with ads. That's a crying shame! One that Google hopes to fix in the near future.