When I went it was just a drop by to grab brochures/booklets/free propaganda then leave to go do other stuff. It's like having all the univeristy's open days all at once, minus a few components (i.e. campus tours). VCAA also have last year's exam papers that were printed in excess to give out. Saves a bit of paper I guess.
That Mental Blank thing was there too methinks. I think I remember making up fake personal details (Inyor Punts, 123 Morelols Avenue, Melbourne 3000 or something) when they gave me a form to fill out. So yeah, be on the watch for bullshit.
If you're interested in interstate universities, there will be representatives there if you have questions/need information and convincing.
Pretty much a marketing fest.