Of course, there are some conditions, as you can read here:
Terms & Conditions: *Optus Pre-Paid Bonus Weekend: Available to Optus & Boost Pre-Paid Mobile customers. Credit expires in 30 days. Minimum recharge $30. Offer starts 12:01am AEST 13/06/09. Ends 11.59pm AEST 14/06/09. You will receive $50 of Rev-Up Bonus which can be used for standard talk and text. Rev-Up Bonus excludes premium SMS and content, international roaming charges, Zoo content usage charges, Instant Messenger, video calling, 966 and satellite calls. Bonus credit will be applied to your account within 72 hours of activation. Customers will be sent an SMS notification upon their Bonus Credit being applied to their balance. For some call types, any free minutes or text included in your calling offer will be used before your Rev-Up Bonus is used. Visit www.optus.com.au/bigweekend for more info. ^SMS to 966: SMS to 966 is free of charge, as is reminder sent to customers on Saturday 13/06/09 at 10.00am AEST. Optus accepts no liability for any loss as a result of a delay in receiving the SMS reminder.