Doesn't progressive scan increase the resolution. Also in a interview with Kobayashi, thats in the April issue of EGM. Kobayashi when asked about the borders, he say's that it wasn't a issue of hardware but giving the player a wider view space. All of you have noticed that when you proceed to aim your weapon, Leon moves to the far left part of screen. Now if you can compare the view space to Splinter Cell, you'll that the view space is wider on RE4.
For the feature nuts there's bump mapping in RE4, which can be seen after killing Salazaars right hand man. Just use your sniper rifle to zoom in on his corpes. Also during the cutscene before the battle with Salazaar you'll see on the large parasite plant flower pedals.