I have not found one yet. I have the Seidio Surface case and holster. The case does not fit when the charging back is on. I also have a CIMO TPU case that fits well enough for me to use when charging the S4 and it fits the holster. The CIMO fits around the four corners and does not come up over the sides all the way but it is good enough until they make cases for this. I also have the Samsung Protective Cover + and it does not fit at all without he charging back on.
I saw in a thread on XDA that the Diztronic matte TPU case fits with the OEM charging back on, but I have no proof that it does.