How has social media changed the way newsrooms work?

BBC reporting:

For BBC News, social media currently has three key, highly valuable roles in our journalism:
• newsgathering - it helps us gather more, and sometimes better, material; we can find a wider ranges of voices, ideas and eyewitnesses quickly
• audience engagement - how we listen to and talk to our audiences, and allowing us to speak to different audiences - and
• a platform for our content - it's a way of us getting our journalism out there, in short form or as a tool to take people to our journalism on the website, TV or radio. It allows us to engage different and younger audiences.

The BBC already has a fair track record of inviting the audience to get involved in our journalism - web forums; debates; blogs and comments, and most recently incorporating comment within our website story pages, particularly on the live pages.
...
Lastly, social media shines a powerful light on all that we do. It can be uncomfortable at times but it is ultimately a great thing. It will help keep us all honest. Those traditional organisations who abandon those core values and aspirations will be found out - there is unrelenting examination of all we do - and those who don't live up to their values will quickly surrender their value to audiences in this new world.
http://www.bbc.co.uk/blogs/theeditors/2011/09/ibc_in_amsterdam.html