How many Anglo-Catholics (I.e. members of the Traditional Anglican Communion or derived churches) are there in the world today and how many have joined the Ordinariate set up by the Roman Catholic Church?
Numbers in the three current Personal Ordinariates are the easy part of the question:
The Australian Ordinariate was only set up a month ago. It appears not even to have a website of its own yet.
As DJClayworth has written, gauging the number of Anglo-Catholics is not really possible. The TAC doesn't have an enormous membership in England, for example.
As far as the Church of England is concerned, which has fairly well-defined metrics such as membership of Forward in Faith or the adoption of various Resolutions, even there those metrics double-count some and leave out others. And while one might count the 100-strong congregation of an "Anglo-Catholic" church as Anglo-Catholics, only 14 adults (and seven children) from mine joined the Ordinariate.
This FaithWorld article says that the higher estimates of the membership of the Traditional Anglican Communion as about 400,000 worldwide. This compares with about 85 million Anglicans worldwide. However the TAC does not represent all Anglo-Catholics. Anglo-Catholicism is not a well-defined group, but it is certainly much larger than 400,000.
Wikipedia has a good article on the Anglican Ordinariates, which includes a list of churches and groups which are part of an Ordinariate. Most of these groups number a few thousand at most. Even members of the TAC groups sometimes refuse to join an Ordinariate.