The ASTM is issuing new (voluntary) guidelines for manufacturers that exclude drop-side cribs. Toys R Us will no longer sell drop-side cribs. About.com has a good article outlining all the issues.
We have a drop-side crib (which is not recalled), and I gave it a good once-over to assure myself that it is safe. We seem to be fine (metal hardware, no indication a gap could form), but I think when we are done, we will junk this crib, rather than re-selling it. Drop-sides are particularly hazardous when purchased second-hand, as it increases the risk of the crib being put together wrong or with missing parts.
Scary stuff! But I am thankful we live in a world where such marginal risks are a big deal, since we have conquered so many risks that once killed babies and children.