The case may also help define what a blogger is. "Blog" is short for "Weblog," which came into existence during the 1990s. The format -- a dated log of comments and links to related Web sites -- has grown in popularity in the past few years.
Last year a blog run by a conservative Minneapolis attorney claiming 50,000 daily visits helped set off the mass debunking of CBS's supposed memos about President Bush's National Guard service. Blogs of all political persuasions are read by millions each day, making bloggers more and more influential.
The Apple lawsuit was filed after a 19-year-old blogger leaked information about new company products weeks before the products were officially unveiled.
Electronic Frontier Foundation attorney Kurt Opsahl, who represents two bloggers named in the suit, argues they're protected journalists. If they're forced to give up their sources, "the public will lose out on a vital outlet for independent news, analysis, and commentary," Opsahl told the Christian Science Monitor.