The 2009 MTV VMAs generated 2 million tweets within 17 hours of broadcast

"Through the "Twitter Visualization" tool used on-air by video blogger iJustine during the VMA pre-show on Sunday night, MTV, social media monitoring firm Radian6 and design agency Stamen tracked more than 1.3 million tweets created about the show by the end of the premiere airing of the show (11:30PM EDT). There were upwards of 1.75M tweets about the show by the end of the second airing (2:30AM EDT), and more than 2M total tweets as of midday on
Monday, September 14."
[Show started at 7pm on Sunday, so midday is 17 hours later]
Source: MTV press release, published by Reuters, 16th September 2009