This repurposing project worked out great because even though we have a baby on the way who will need a crib, our old crib was a drop-side, used crib that we were no longer comfortable with due to all the crib recalls and safety issues. I feel perfectly justified buying a new crib for the new baby, especially since we were able to repurpose the old one instead of tossing it.
Here's the finished headboard. Basically, my husband took the two ends of the crib and used metal brackets to attach them at the back. Then, he used furniture wall straps to tether the headboard to the wall--nice and secure. This headboard could fit up to a queen-size bed, and I love that my daughter still has a piece of her babyhood with her as she sleeps.