At the moment Virgin Blue cant use the name outside Australia due to a SQ agreement with VS hence the use of Pacific Blue when it was launched.
The idea of using V Australia is apparently so if at some stage in the future DJ can use the Virgin name over the Pacific it will be easy to change to Virgin Australia. Also the livery is very similar to the VS one so that will be easy to change also.
So give it a couple of years, SQ sell there stake in VS. Branson gives Godfrey the nod and all of a sudden you will have Virgin Australia.
Cant wait for the 777's to start.