According to CVG, there's a new mode being added to the Wii port of The House of the Dead game that was originally released on the Dreamcast. Previous information made it seem like it was only going to be a direct port.
The new Extreme Mode can be unlocked for House of the Dead 3 after completing both of the titles. It quickens enemy attacks, shrinks bullet blast radius, quickens shotgun reloading and adds a melee attack.So, basically, it's just a very challenging game mode as well as adding an up close and personal attack action. Between this and Resident Evil: Umbrella Chronicles on the Wii, I'm pretty much in zombie heaven!