This has always been the case at many airports all over the world, particularly at terminals with international flights. rufus102 was at Sydney's international terminal. It is becoming a universal requirement - airports are having to build extra bits to their terminals to ensure that this happens.

If for no other reason, it makes sense for terminals with international arrivals because the airport simply can't control how good security is at the airport from which the flight departed. If you don't put all transit and connecting pax through security, you leave a large hole in your own protection ready to be exploited by bad guys.