According to a recent interview with Tim Willits and Matt Hooper of id Software at Tomshardware, DOOM 3 is set to expand when we get the new PC expansion - Resurrection of Evil.
Following the events of DOOM 3 and featuring new locations, characters and weapons, including the return of the double-barrelled shotgun, DOOM 3: Resurrection of Evil picks up from where DOOM 3 finished. Naturally, as an expansion pack it does require the full retail version of the original DOOM 3 to play. There are apparently many new surprises in store for us.
Among the new weapons to be found in Resurrection is the grabber gun. Reminiscent of a certain weapon in Half-Life 2, the grabber allows players to swipe objects and projectile weapons, and fling them around the room. You can even grab small demons and toss them back at their friends, killing two birds with one stone. Using the grabber well requires timing, but once mastered, it is a powerful weapon. For example, grabbing an Imp's fireball and flinging back at the hapless demon will result in its instant demise. The grabber can also be used to reach out-of-the-way weapons and health packs.