Alecia Swasy studied this for two years, and published her findings at Poynter:
For reporters, Twitter expands their readership to an entire globe that was once limited to geographic circulation boundaries. The best example of this came from the Tampa Bay Times and Craig Pittman, one of the country’s top environmental reporters. His presence on Twitter got the attention of the editors of Slate, who asked him to do a month-long blog. It also helped him land a book contract on news of the weird in Florida.
In almost 4 years as a journalist, it's hard to overstate just how essential Twitter is to my work. I get news, connect with friends and colleagues, share my writing, and more all on Twitter. The service—and the business—has its problems, but it's an incredibly valuable tool to me and many others. In many ways, Twitter has quite literally made my career; it's that instrumental to what I do. I don't think I'm alone in that sentiment.
In hindsight, this piece I wrote seven years ago mocking Twitter now reads as a perfect example of naïveté on my part. Reading it today makes me cringe. It's terrible.