Just curious why someone in America would apply for it though? Is it because they haven't decided on what specialty they want to pursue? The fact that it was easy to find these types of programs must mean that there are actually a substantial amount of people interested in it.
transitional years serve the same puporse as prelim years. there are 2 types of prelim years, med and surgical. certain specialties require a year of postgrad training before you start. many do not specify transitional or prelim, while others may specify the type of prelim year.
the difference between the transitional year and prelim year is the prelim year is often very similar, if not identical, to the first year categorical residency position and the transitional year is very similar to a rotating internship. the transitional year also has lots of electives available. from what i've read the transitional year is much, much, more relaxed than prelim spots too.
often it will be required to match into both your specialty and the transitional/prelim year in the same year. say you are applying for rads, you apply this year to start prelim next year and to start rads the year after, though it is possible to do the prelim/transitional year with no residency secured for the following year and reapply the following year. however, the biggest problem with this, again from what i've read, is that most the specialties requiring transitional and prelim years are very competitive. this means that you could be stuck without a position altogethor after the prelim/transition year. but its more likely that you wont even get that transition/prelim year because the people matching into them are also the ones concurrently matching into highly competitive specialties.
because the transitional years are relaxed in comparison to prelim years with lots of electives they are highly desireable. this and that there are fewer transitional programs makes securing a transitional year highly competitive; it can be hard for US MD grads to get one. thus, i sure wouldnt make a plan of doing a US transitional year and then returning to Aus. in all likelihood if you couldnt get into a US MD school, you are unlikely to get a a transitional year.
also, you'd still have to deal with the whole permanent residency issue. the processing times for applying for registration after finishing a US transitional year may be long considering they'd have to approve its equivalency to an Aus internship. i believe upon completing an Aus internship succesfully you just submit a form and gaining full registration is pretty much automatic. once you have registration a hiring hospital can sponsor you for a visa, but in doing US transitional you'll be overseas, which will not provide very promising networking oppurtunities for securing a job in an Aus hospital.
please correct me if i am mistaken.