Jul 282013
Update: Facebook now allows for retargeting directly through their Custom Audiences from Your Website feature.
In the world of Facebook retargeting ads performed through Facebook Exchange (FBX), one does not do business directly with Facebook; rather, you must use a qualified Demand-Side Partner. I have yet to find an official list of DSPs who work with Facebook, but the list of DSPs found here is the most thorough that I have found so far.