If I had to use one word to describe my experience with live streaming, it would be frustrating. I haven't live streamed anything myself, nor have I participated directly in an event, but I have spectated a few. A couple of months ago, I tried to watch the live stream of Carnegie and Greenaway ceremony, but technical problems - drop outs, freezes and buffering (my joke at the time was "Buffer Slow Soldier, more like!") - made the event pretty much unwatchable.
I have watched a few archived (non-live) streams of hangouts, but they too are usually beset with technical difficulties - drop outs, variable sound and image quality and sound lag (which often results in long, awkward silences followed by everyone talking at the same time). I feel the technology is not quite good enough yet. And this is probably a poor reflection on me, but I rarely have the time, inclination or patience to sit and watch an hour-long video of variable quality.
In contrast to Thing 9 (screencasting), I can't really see myself life streaming anything at work any time soon. Maybe I'm still too new to my role to have come across a situation where I will find it a useful tool. The only thing I can see myself using it for at the moment would be for "attending" conferences from afar - but the above-mentioned technical issues (currently) make this substitute less than ideal.
I am, however, willing to be convinced...