The people I work with mostly all have their own servers/ iT team etc. on the back end to deal with the distribution, streaming end of things (think big corporate & gov't groups). What actually shows up on the job-site can range from a single camera/laptop setup, all the way up to full-on tv broadcast trucks.
What shows up on the gig doesn't often dictate the size of the audience who will be viewing either... I've done single camera/laptop webcasts that were viewed by tens of thousands of people all logged on at the same time around the globe.... And huge (on-site) productions where the webcast audiences were much more modest. The back end (off-site) systems seem to really be where the bulk of the workload is handled though.
My experiences with google's technology has been as good as any other I've been involved with... But those jobs were actually for google, with their people at the helm.
Like anything else, the answers to your specific questions will be found in your specific needs, budget and expectations.
