The battle has officially begun. It was only a matter of time before two of the most powerful Internet companies in the world got into a public tiff.

This morning, the PR firm Burson-Marsteller confirmed it was hired by Facebook to spread negative stories about Google’s social networking tool, Social Circles. In a slew of e-mails sent to the news media, Burson alleged that Google is using Social Circles to “scrape and mine social sites from around the web” and share that information without the consent of users. Facebook is claiming they didn’t authorize the anti-Google smear campaign.

In addition to the news released about the PR campaign, a number of factoids floating through the interwebs show that perhaps, just perhaps, neither Facebook or Google have been the most up front with the public.

At the end of the day, this competition boils down to trust. Who do users trust more: their friends or a search engine? If the social web is the key to the Internet kingdom, Facebook shall reign victorious. Of course, if Google acquires a trusted social network that drives global news and publicity for brands, this battle could turn into a full-fledged war.

Where do you get your information, Facebook or Google? Don’t be shy in letting us know. You can be sure both companies are watching quite closely.