I would be checking that. It appears to be a new thing and according to the CBA anyway the Goverment says that because it is gambling (and all gambling is bad, ok) the purchase is a cash advance and therefore should be paying interest on it.
I tested this last night by backing the Huss to top score in the Big Bash game.
Just checked my online statement and it is definately there as a "credit card purchase"
And Hussey top scored too