Billboard and Twitter have launched a new interactive chart – the Billboard Trending 140 – that ranks shared songs in the U.S. by analyzing the fastest-moving tracks, in terms of the acceleration of shares via tweet, over the past hour. The result is a real-time presentation of the most-shared tracks in the country. Billboard plans to share weekly summaries of the new chart’s findings in the form of a ” Billboard Twitter Top Tracks” chart, via both the magazine’s website and print publication.