[tgflynn]

> The only way we would find something is if they pointed a VERY powerful noise source directly at us, or us at them.

Do you mean we could detect ordinary technological EM radiation if we pointed a sufficiently high-gain antenna at the transmitting planet ?

Otherwise if SETI assumes someone is sending an interstellar signal on purpose, I would question its value, because there's no strong reason to think anyone is doing that. I realize we did it once, but an argument can be made (and has been) that it was a fairly stupid thing to do.