During the WPPI show B&H offers some additional savings on Tamron lenses if you use promo code 2505524955085 during checkout. The bonus rebates includes also $200 off on the Tamron 24-70mm f/2.8 Di VC USD lens. This offer is valid till March 13, 2013.
Update: B&H fixed the issue with the promo code and now it should be working correctly.