The Games Radar has the latest article/preview about Doom 3 which includes the usual info about how Doom 3 will be uber scary and of course comparisons to classic Doom, along with a few interesting tidbits which you may or may not have seen before:
No longer will you be able to swap between the BFG and the chainsaw at will. Even the torch, a new addition to the series, takes up space. When you crawl through the blackness, you need to make a choice. Do you face the dark, pistol in hand, feeling your way through, or unarmed, but with a clear, lit path?
Also they mention a release time area of May 2004, so with that as well as the speculated April release, it surely looks like Doom 3 is just around the proverbial corner. .soon.