Apologies for the poor website link! I actually saw this in the newspaper.
You must open the accounts in a branch.
Extra conditions:
Use your card five times before 31 March and if you are in the first 10,000 qualifying customers you will get the $50.
Oh and you will also get a chance to win a trip to meet the Australian cricket team in the West Indies…meh
they are getting stingey? they have been offering $100 previously
direct link http://www.commbank.com.au/personal/start/cricket.aspx