Historically, most normal mapped ships were modeled to their "production" poly level, and then had their normal mapped detail added in Photoshop, using an Nvidia plugin to create 3D detail from 2D heightmaps. This works fairly well for a lot of cases, but not for everything. The three original "special" ships (Prometheus, Valkyrie and Marauder) were all made with this method, as are the older ships that I'm currently bringing more "up to date" with added normal and specularity maps.

Luis's new ships, on the other hand, are being made using a different method. He is creating two models for each ship, the first at the "production" polygon count (say, around 1500 for a smaller ship, or upwards of 5000 for a bigger ship). The second is a detailed high-poly version (upwards of 200,000 polygons) which has its greater detail then "cooked out" via render-to-texture onto the lower poly version in the form of a normal map. The more complex lighting surface normals of the high detail version are then preserved on the low detail version, with the lower poly count. This method has been widely used in a number of modern FPS games, Doom III and HalfLife 2 amongst others, and is generally a great way to add complex model detail onto a game-usable version of the model. It does have some caveats, some things don't always cook out quite right, and some aspects require tweaking, but overall it's a good way to get a lot of base detail on the normal map. This is then further tweaked at a 2D level in Photoshop, and the other materials are built to accentuate the features of the normal map, creating a more realistic looking spaceship.
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