DEPARTMENT OF THE ENVIRONMENT. 2013. Australia’s bioregions (IBRA) [Online]. Available: http://www.environment.gov.au/topics/land/national-reserve-system/scienc...
"... (the) National Reserve System is provided by the Interim Biogeographic Regionalisation for Australia (IBRA). IBRA was developed in 1993-94 and is endorsed by all levels of government as a key tool for identifying land for conservation under Australia's Strategy for the National Reserve System 2009-2030. The nationally agreed regionalisation was published in Thackway and Cresswell 1995, An Interim Biogeographic Regionalisation for Australia: a framework for establishing the national system of reserves.
"IBRA is updated as improved spatial mapping and information on vegetation communities and ecosystems becomes available from state and territory agencies. For example, in 2000 a review was undertaken to resolve boundary and data issues, which led to the development of IBRA version 5.1. Further information on this review can be found at: Revision of the Interim Biogeographic Regionalisation of Australia (IBRA) and the Development of Version 5.1. - Summary Report."
http://www.environment.gov.au/land/nrs/science/ibra
Looking at the current IBRA maps: (IBRA7)
Australia's 89 bioregions (PDF - 2.57 MB)
Australia's 419 subregions (PDF - 4.95 MB)
IBRA7 boundary changes (PDF - 1.88 MB)
See also NRM Regions Australia http://www.bloggerme.com.au/nrm-regions-australia