When I think of twitter in relation to journalism I immediately think of breaking news and how twitter can help journalists literally get the scoop first. Where else can they find a live feed of information straight from the source, whilst sitting in the comfort of their own office. Whether the news is a mass murder or a natural disaster being able to read peoples comments who have lived the event is so valuable to a journalist. Also through the use of twitters advanced search engine and hashtags journalists can easily find sources for their stories. If you have a big enough following on twitter you can ask a question you may have and be answered in seconds by your many followers. Obviously you will have to confirm those answers like you would in old school reporting too.
Also many public figures and organizations use twitter as a forum to make announcements. Following certain professionals on twitter will make sure a journalist receives this information first. This article from The Telegraph lists some notable announcements made via twitter ranging from a celebrity divorce to retirement. Any of these announcements could create beneficial leads for a journalist looking for a new story.
Twitter can save journalists time in the long run, however I do understand that it can also waste time if a journalist gets sucked into scrolling through tweets all day and responds to everything they are tweeted. But if twitter is used in a disciplined manner like above mentioned it can save time in pursuing breaking stories, finding sources, getting answers to your questions and coming up with story ideas.
Distribution of content is another vital role any social media such as twitter or Facebook can provide to a story. Sharing stories via either medium creates a domino effect which can give a journalist more and more of an audience, equaling a bigger name in the journalistic world which of course everybody wants. I also think social media allows the conversation to continue after a story has been published and creates a forum for the public to voice their opinions and allows them to be more involved with the journalistic process.
Twitter and Facebook are fun, and I think that it is important for a journalist to have a break in their day and laugh at a funny tweet from @theonion. Utilizing social media will only help a journalist grow, and I think in the near soon an online prominence will mean everything in the news reporting world.