I found this on google, there are many more information on there.

Eucalyptus Rust
Eucalyptus Rust (Puccina psidii), or guava rust, is the only rust disease that attacks the eucalyptus tree. This is a serious disease that attacks young shoots, cuttings, seedlings or a mature tree that has sustained damage. This disease causes deformed leaves leading to defoliation and stunted growth. This disease often kills eucalyptus trees. Eucalyptus rust is spread through spores. People who work or visit places where the eucalyptus tree has rust should thoroughly clean their clothes so they do not spread this disease elsewhere. The first signs of eucalyptus rust are tiny raised spots on infected areas. These areas turn the colour of egg yolks in a few days.

It's hard to say whether this is Guava scale or Eucalyptus gall wasp, which is fairly newly arrived here. Google both and compare the pics to your own tree to try to decide...

Considering that eucalyptus used to be untroubled by pests here, its somewhat worrying that ever more pests and diseases are attacking more and more plants...