So here’s the good news about the news. Amid all the arguments about bias, the intrigues about the anchors, the high-fiving about the ratings, a devastating tragedy like the tsunami reminds us all of this overriding fact: The combined efforts of the networks, cable and broadcast, made the world keenly aware of the magnitude of the tragedy and the mobilize resources to aid the victims.It was the first litmus test in what is certain to be a watershed year for TV news divisions. News divisions across the dial are in for some major upheaval in the months ahead. They face renewed scrutiny from their corporate parents and sharp questions about their nimbleness in a fast-shifting media universe. Coming soon are Dan Rather’s retirement and Viacom’s report on the “60 Minutes” controversy that cast a pall over his exit. Brian Williams has yet to prove himself as a worthy successor to Tom Brokaw. ABC has yet to reach a decision on the future of “Nightline.” CNN is struggling to regain its footing in the face of lacerating competition from Fox News. The most comprehensive coverage of the catastrophe last week came from CNN, which reaped the full benefits of its 24/7 news cycle, robust international bureaus and savvy field reporting by hotshot anchor Anderson Cooper. Network news anchors Williams and Rather, plus ABC’s Diane Sawyer, arrived this week in the tsunami-ravaged regions. Their coverage may restore some of the credibility news divisions lost during the presidential election. It’s moments like this when TV news provides the connective tissue of our increasingly interconnected world.