There was an article in one of the bike mags about carbon fiber bike parts. The thing about carbon is that when it fails, it fails catastrophically. Because of that, Easton builds its carbon fiber handlebars 10 times stronger than their aluminum ones. Imagine how light they would be if they didn't have the huge safety factor built in!
Still, I'm a retrogrouch and won't be putting any carbon fiber anything on my bikes. I've seen plenty of pictures of snapped carbon seatposts. Carbon seems like just the latest marketing ploy to remove cash from easily duped consumers. Its kind of like what happened to steel frames - aluminum was so sexy because of Klein and Cannondale so all the bikes became aluminum. Go ride an aluminum framed hardtail back to back with steel and you'll quickly see why this was just a marketing driven thing rather than an improvement.