Sydney's transport smart card project (Tcard) has been abandoned and the Victorian project (MyKi)is to be having problems. Technically, smart card ticketing systems are very simple, with hardware available off the shelf. But transport smartcard projects frequently have problems, where the transport companies fail to rationalize their fee structure before implementation.
The hardware for the Victorian system seemed to be workable when I tried it. Projects seem to have been successful in Perth (Smartrider), London (Oyster Card), Hong Kong (Octopus Card) and Beijing (Yikatong). There is a UK based Integrated Transport Smartcard Organisation.
In contrast to the problems with public transport smart cards, the e-TAGs used for electronic toll collection on roads in Sydney and Melbourne are working and interoperable. Perhaps the Australian Government should get the states together to produce a system which would work on public transport and toll roads across Australia. This need not use the same hardware for public and private transport, but could use the same back end payment settlement system. In this way motorists would be encouraged to use public transport as an alternative to driving on toll roads.