For millions of Internet users, the collaborative online encyclopedia Wikipedia serves as a trusted information resource, its articles covering more topics than most can imagine -- almost 2.2 million entries in English alone. Wikipedia's own readers, their expertise and their dynamic scrutiny help maintain the site's accuracy, as well as the neutrality vital to its reputation.

At least, that is how Wikipedia is supposed to operate.

In December 2007 the giant wisdom-of-the-commons encyclopedia was the Web's 8th-most visited site, according to Alexa data. Type just about any proper noun into a major search engine and a Wikipedia entry about it will probably pop up in the first page of results.

But despite all the eyeballs scanning it, and the efforts of a large volunteer work force, Wikipedia has become something of a battleground for the truth, or, at least, a kind of operating history. Beyond Wiki-debates churning daily about obviously controversial topics such as abortion or gun control, or the biographies of U.S. presidential candidates, Wikipedia's articles are becoming targets for anyone with a stake in making sure history unfolds according to proper talking points.