There are actually tricks that work. They won't fool experts, but you can go a long way to making it 'feel' more like film. Unfortunately if you've already shot the project you have missed your opportunity to do the most important thing, which is light the project like you would light for film (assuming you didn't). The next steps is to de-interlace and then use QT Pro or Compressor to bump the framerate to 24 fps. There is also an AE plugin called Magic Bullet that is specifically made for making video feel like film. It is very expensive (I think $1k), but I hear it works wonders.
The basic things that make film and video feel different are as follows:
• film is lit differently
• unless the camera you shot with is incredible, film has better color
• film is 24p, not 60i
• film has darker blacks
• film has grain that is tough to simulate (the best simulation of this I've seen was in Shake. Bling bling).
• If you can afford to shoot with film, your production value will be higher in general. you will have nicer gear, better lenses, better sound, better actors, better sets etc.
I'm waiting for
this to come out, because it looks like a very affordable way to do some basic tweaking. If you have FCP, this might be just what you're looking for.