Quoting James Davis on Monday December 04, 2006:
| If you guys recall, several months ago I bought up the issue of the 
| wildcards on au.com.au, and com.com.au was causing a lot of issues with 
| certain network setups and certain operating systems.

They were previously blocked, but the auDA Names Policy Review Panel in
2004 determined that "the technical basis for maintained the restriction
is no longer relevant". I'm not sure what study was performed to come to
the conclusion, but their final report reads:

    Recommendation 4: Restriction on domain names that match existing TLDs

    Recommendation 4:

    The Panel recommends that the restriction on domain names that match
    existing TLDs be removed. Current policy: The auDA Reserved List
    contains existing ccTLDs and gTLDs, which means that people cannot
    register two-letter domain names such as "uk", "nz" and "jp", or other
    domain names such as "com", "name" and "museum". The basis for reserving
    gTLDs and ccTLDs is to comply with IETF standard RFC 1535 (refer to
    http://www.ietf.org/rfc/rfc1535.txt?number=1535.)

    Rationale:

    The Panel notes that the technical basis for maintaining the restriction
    is no longer relevant due to DNS technology developments since RFC 1535
    was drafted over 10 years ago. The Panel further notes that in the
    past the restriction has been imposed inconsistently, and hence some
    restricted names are in fact being used with no apparent ill effect.

See http://www.auda.org.au/pdf/nprp-final-report.pdf

kim