Because this calendar is based on the equinoxes and solstices the North and South will celebrate opposite holidays on the exact same day. This means you and I will always celebrate on the same days, but be having opposite holidays.
This means that if you want to know the date you'll celebrate Yule, you can look up when the Northern hemisphere celebrates Litha. This is pretty convenient since you don't need to recalculate anything, you just need to take information from a Northern site or book and just slide everything forward.
The Southern hemisphere sabbat dates this year are...
Lughnasadh ? 2 February 2012
Mabon ? 20 March 2012
Samhain ? 30 April 2012
Yule ? 20 June 2012
Imbolc ? 1 August 2012
Ostara ? 22 September 2012
Beltane ? 31 October 2012
Litha ? 22 December 2012
Other seasonal pagan holidays can be similarly changed to be Southern hemisphere appropriate.