I believe it was stated in The Elegant Universe (Score 1, Interesting)

by Brian Greene that he thought it might be possible to detect a graviton using CERN's Large Hadron Collider when it is completed. This may also help to substantiate some of the ideas of string theory... namely that the energy of a particle (string) is inversely proportional to its "size". Gravitons may be "large" enough to be detected when the particle smashing fun begins! I really enjoyed reading this book BTW. Recommended reading!