It's not known exactly when the demo will be available to pre-ordering folk. Stores should have the codes now, and codes for online orders will start going out February 2.
Sony had said that the demo would be exclusive to GameStop pre-orderers until the PS3-exclusive shipped, which is technically true, as the Guerrilla Games-developed shooter will ship to retailers at least one day in advance of its February 27 release.
The publisher also justified its decision to offer early access to the demo as a GameStop pre-order incentive, stating that this approach "helps seal the deal." Sony Computer Entertainment America product marketing VP Scott Steinberg explained:
Offering a playable demo to motivate preorders speaks to our confidence in the appeal of a game such as Killzone 2. We take this approach when we are convinced that the experience will cement a consumer's interest in purchasing. Retailers will then merchandise those demos within their stores and online to maximize their visibility. Through this process, consumers are often times able to reserve their copy of the final game, which provides an incentive to purchase and helps seal the deal. We also offer demos on the PSN, which we have done in the past with great success, and will continue to make that available. Killzone 2, for example, will have a downloadable demo launch in North America the week that the game is launching, for consumers who prefer that option.