It's basically a restricted mileage registration that cost under $200, compared to the $800ish that a V8 currently cost in Qld. Here are a couple of short descriptions of the Hot Rod and Vintage Concessional rego deals (in Queensland).
http://www.transport.qld.gov.au/qt/d...c?OpenDocument
http://www.transport.qld.gov.au/qt/d...9?OpenDocument
Because of the driving restrictions placed on the car as a result of the cheaper rego, it might not suit a lot of guys. I have an XY Ford on the Historic rego, and it's nice to know that I don't have to pay top dollar for my rego on it when I only drive it once or twice a month.