At the stroke of one minute past midnight on 9 July 2011 (local time), the new Republic of South Sudan came into existence. See video news reports
UK Daily Telegraph
See also reporting by France24.
Flag of the Republic of South Sudan
It is a great day for the South Sudanese people who have struggled through five decades of civil wars. In Australia, which has one of the largest South Sudanese populations outside of Africa (some 30,000), community celebrations are being held across country.
See websites of the Government of the Republic of South Sudan and the Embassy of the Republic of South Sudan in Washington DC.
A good primer from PBS