Special American visa category for Australians

This morning’s papers are reporting on the creation of a new visa category that will make it easier for Australians with professional qualifications to live and work in the USA. The category appears to be available only to Australians. The reports suggest that this is the first time that the USA has created a visa category applicable to only one country.

Is this true? I find it hard to believe that there have never been examples of country-specific US visa categories before. What about Canada?