Apparently this is coming to a close:
"Due to overwhelming demand our limited supply of free exam vouchers is running low! This limited time offer will end on Friday, October 9, 2009 at 5:00 PST – after that we'll revert back to our traditional 50% offer, still an outstanding value. It's not too late to pass a pre-assessment exam in order to receive your certification exam for free as 100% discounted vouchers earned on or before October 9, 2009 will expire on November 30, 2009. So please register and take your certification exam before the discount voucher expiration date."