I think that a few people are missing one of the main benefits of ADS-B. The system allows for a pilot(with the appropriate equipment) to be aware of another aircraft without ATC assistance.
In the USA yes, In Australia, no. We are implementing ADS-B out, not ADS-B in like the US.
Yes, you can pick up nearby aircraft with non-TSO'd equipment, but you can do that now with mode C. You don't need ADS-B.