While it substantially trails rivals in display ad revenue, Facebook pulled ahead of Yahoo’s ad delivery rate for the first time in Q1. According to comScore Inc. as reported in The Wall Street Journal, Facebook  delivered 176.3 billion display ads on its website over the first three months of 2010, more banner ads than any other Web publisher in the period and 16.2 percent of the total ads served. Yahoo served 131.6 billion banner ads to Yahoo users, and Microsoft served 60.2 billion. The growth also reflects increased demand from both small and large advertisers, comScore Chief Marketing Officer Linda Abraham told WSJ.

The data don't include ads that Yahoo and Microsoft delivered to other Web sites through their networks, a major source of revenue for each.

But the social networking site trails its rivals in revenue. Facebook  earned more than $500 million in 2009 and is forecasting revenue of more than $1 billion in 2010. Yahoo earned $6.5 billion in revenue in 2009, mostly from advertising.

For the last month, comScore also reports that Americans conducted 15.5 billion core searches. Google Sites lead the market with 64.4 percent share of core searches conducted, followed by Yahoo! Sites (up 0.8 percentage points to 17.7 percent), and Microsoft Sites (up 0.1 percentage points to 11.8 percent). comScore says both Yahoo! Sites and Microsoft Sites have experienced gains due in part to the introduction of new site navigation experiences that tie content and related search results together within several channels. “These features provide search results to users as they navigate through topical content and meet comScore’s established criteria for counting search queries.” Ask Network captured 3.7 percent of the search market, followed by AOL LLC with 2.4 percent.