Whether one can claim losses on a company that goes belly up as...

Whether one can claim losses on a company that goes belly up as Capital Loss or Income Loss depend on whether the person is an investor or a trader.

Obviously the number of trade done per year will be one of many criteria the ATO looks at on a case-by-case basis.

Do a search on the ATO website. You may also like to read this article:
http://www.smh.com.au/business/money/tools/guides/investment/trader_def.html

For most people who are "Investor" you can only claim capital loss usually only after the liquidator/administrator rule shareholders are unlikely to recover any proceed from the company. This may take a while.

If you are worry about waiting, you may perhaps consider selling your shares and then buying it back. The costs of selling and buying back the shares may justify the claimable capital loss compared to waiting for the administrator's ruling.