As far as I know, the project for a new World Trade Center is already approved and doesn't resemble the old one. However, today I saw by chance an online petition by The Twin Towers Alliance to rebuild the towers. If you support the idea, you can express your opinion at http://www.twintowersalliance.com/petition/.
Although nothing can bring back the lost lives, I would feel a bit better if I could see the towers again at their place. I still feel pain in the heart when their image appears in some old movie.