UPDATE: Just a quick note to add here. Bethesda informs us that the seven new levels comprising The Lost Mission is entirely new content that's been created especially for this remastered edition of the game. This isn't stuff that was left on the cutting room floor back in the early Aughts. Most of you probably assumed that was the case given how much content The Lost Mission amounts to, but it's nice to have confirmation.
ORIGINAL POST: Bethesda has a surprise for you Doom fans today, in the form of the newly announced Doom 3 BFG Edition. Coming this fall to Xbox 360, PC, and PlayStation 3 -- the series' first appearance on the PS3 -- the BFG Edition includes Doom 3, the Resurrection of Evil expansion pack, and seven new levels bearing the title "The Lost Mission." Also included are Doom and Doom 2. Buy this, get all the Doom.
That sums up the bulk of it. Doom 3 BFG Edition includes both the single player and multiplayer sides of the game, so you can look forward to shooting up your friends online as well. Only one gameplay tweak is mentioned: an armor-mounted flashlight. As anyone who played Doom 3 knows very well, this is a fantastic and very welcome addition. Take a peek at the new face of Doom 3 in the just-released trailer up top.