For the last month it has been the holy month of Ramadan. Now it is Eid al fitr. Eid started today. Ramadan and Eid, like Easter, start and end according to the cycle of the moon.
There is a moon sighting committee which met last night to determine that the Shawwal moon has been sighted and to declare the end of Ramadan and the beginning of Eid.
There are public holidays for Eid, but it has not been possible to set the exact days of the public holiday. If the committee did not sight the moon last night then Ramadan would have continued for another twenty four hours.
This article explains it better than I have done.
And you know what Australians are like when it comes to public holidays.