Actually Google receives 25% of the question amount, in addition to the 50 cent listing fee.
Reference, the Google Answers FAQ's:
How much do answers cost?
http://answers.google.com/answers/faq.html#cost
..."There is a non-refundable listing fee of $0.50 per question plus an additional 'price' you set for your question that reflects how much you're willing to pay for an answer..."
How much should I pay for my question? What price should I set?
http://answers.google.com/answers/faq.html#howmuch
..."Three-quarters of your question price goes directly to the Researcher who answers your question; the other 25 percent goes to Google to support the service..."
~~Cynthia