Lol, the game is being worked on, and it's going well, don't worry.
It's because it's been a while that we know it's going to be almost done.
The reason it seems like "ages" is because it was announced before any real work was done. Games are usually at least halfway done before they are announced publicly.
But yeah, don't worry man, Doom4 sneek peaks and stuff will be showed at this year's QuakeCon. Last year they said they didn't show anything because they wanted RAGE to be the highlight of the night.