Todd Howard confirmed it on the (GameSpot? Might have been GameTrailers) interview. I'm crossing my fingers in hopes that they also add arrows as craftables!
Ah, it was the G4TV one. Sorry, I've watched too much E3 stuff. Anyway, he mentioned crafting bolts at 2:30, right after mentioning Dragonbone Weapons.
All that I know is that you can craft bolts, have an ordinary crossbow and 'even get a dwarven crossbow' I want to know if there are more than 2 varieties (glass elven steel etc) or just a regular one and special dwarven one.