The helmet "opens to reveal art book, Super Voucher and Killzone 3 game." That "Super Voucher" grants access to a soundtrack, a dynamic theme, a Retro Map Pack of two Killzone 2 maps, and full weapon and ability access and double XP for the first 24 hours of multiplayer. In addition to all that, there's an even smaller Helghast in the package -- a 6.5-inch "Cloaking Helghast" figure.
Notably absent from the package: "Helghast goggles," the "Blood and Thunder" pack, or a gift card, as revealed on the Killzone 3 site last week. Either that stuff is reserved for a European special edition, or it was merely placeholder text.