I think that was a limited time deal. According to a Gossamer Gear email/newsletter:
October Deal - From now until November 15th all domestic orders over $45.00 will ship for free using the coupon code 10IN2011. This offer is only good on domestic (US) orders and we reserve the right to ship by whatever method we choose - could be ground, priority, first class mail, etc. Remember you MUST be fully logged in and registered for the coupon to work and the offer is not retroactive.