All that Twittering about TV? It really does boost TV ratings. So says Nielsen, in a new study that Twitter executives, among others, will be delighted to see. It’s the first research that conclusively states that an increase in Twitter commentary about a TV show can increase viewership of that same show as it airs live. That’s a very big deal for Twitter, because it will be seen as validation for a pitch Twitter has been making to TV networks and advertisers for a couple of years: Work with us, and we’ll help you get more eyeballs on the stuff you put on TV. And that pitch is more important than ever, as Twitter starts to get very serious about ad money, and about an impending IPO. Caveats? Sure: Start with the word “can”: Nielsen doesn’t say that this always happens, just that it does some of the time.