Custap Berry NOT released, if you mean for Gen V, since I know for a fact you battle Gen V. Only Salac, Apicot, Ganlon, Petaya, and Liechi are available. Join Avenue is the only place at the moment for those stat raising berries.
Source (Scroll to Florist)
For Gen IV, however, it IS released, as darkgoku mentioned.
Custap Berry is now released as a participation prize in the 2012 VGCs Winter Battle.