Depending on how you look at it this is either a very cool thing, or a cheap way for the Government to do useful stuff with its data, or both. The NSW Government has a rich vein of open-source data available through data.nsw.gov.au and while some of it is pretty much junk (one-page PDF statements) there are some deep and potentially very useful datasets to work with.
All-in-all this could be a great fun event for a team of coders and thinkers.
There are sites in Sydney City, Manly, Parramatta, Newcastle, and the Hunter Valley. The event runs from 6pm on 29 July to 5pm on 31 July. Registration and more information is here. Registration is free and there’s free food and the like available through the weekend – and prizes out the other end.
If nothing else it’s a chance to use the words ‘government’ and ‘hack’ in the same sentence without immediately looking furtively over your shoulder.