I remember when my agency started its Facebook page. We were just going to use it as another outlet for our news releases and blogs. Hah!
The public started us asking questions, and now our FB page is more an extension of our ombudsman efforts than a news outlet, and it takes the equivalent of an FTE to monitor and reply to the beast.
I’m waiting for Google+ to grow up a little, and for some tools to appear that will make it easier to manage multiple social media tools. I think Circles would let users self-select the kind of info they want and ward off social media fatigue a little longer.