Greg Sandoval reports in cNet News:
Though he became best known as a conservative commentator, Andrew Breitbart was also one of the early proponents of Internet news. According to the Washington Post and Breitbart’s own site, the Los Angeles native died this morning at the age of 43. The cause of death was not disclosed.
In the mid-1990s, Breitbart was among those who recognized the impact the Web would have on communications and began corresponding with Matt Drudge, creator of the Drudge Report. He would later served as an editor for the site and become a close Drudge friend and ally.
Drudge later introduced Breitbart to Arianna Huffington and Breitbart helped her create The Huffington Post. Both the Drudge Report and Huffington Post would become two of the most popular Internet news sites. Breitbart eventually launched his own Web sites, including Breitbart.tv, and Big Hollywood.
This WIRED article “How Andrew Breitbart Hacks the Media” from April 2010 provides much more background.