Scott above has it right. Its a legally binding contract. If you breach the contract, Cricket Australia, would be entitled to damages. The damages would relate to the level of income they might have lost by you posting on facebook to damages for defamation if you post an image that has a negative impact on a players reputation or standing.
By making the photos publicly available, there is always a risk that someone else might take your pictures and use them in some profit making venture - eg a Calendar in India, cricket bat ads in South Africa. If they can trace the photo back to you, then you would be in a very awkward spot as far as damages go.
However, I'd suspect the chances of this would be very low and for all intensive purposes, Cricket Australia would not suffer any damage from you posting photos on facebook etc, therefore they wouldn't receive any damages (maybe $1) and therefore they're not going to commence expensive legal action against you. And if they were concerned about anything you're doing, I'd suspect CA's first action would be to write a letter reminding you of the ticket conditions and ask that you remove the photos.
PeterJ, I think you're confusing a series of court cases from the 80's and 90's. Typically, they'd involve a business like a carpark. You would drive in off the street, go through a boomgate and get a ticket, and only then see the rates or conditions. Because you had no opportunity to see the conditions before entering the carpark, they weren't valid (and is why you now see them outside of the carpark as you enter). Banks and other financial companies are also subject to a number of credit and lending regulations and they also have a higher standard of equitable conduct to meet. Many of these came into place after banks thought it was a good idea to sign 80 and 90 year old's up as guarantors for grandkids' loans, lend money to people from overseas who couldn't speak English and didn't really know what they were doing etc etc. Therefore to avoid possible accusations of unconscionable conduct, they go through all of the conditions, make guarantors seek independent legal advice and now even have to ensure that borrowers can comfortably repay a loan.
As Ticketmaster make their conditions available before buying the ticket, they are valid. And I assume if you buy them at the grounds, they'd have the conditions listed in the ticket office for reading before purchasing. Anyway, I'm off to the Gabba in a few weeks - where did I put my vuvuzela?