An email I received from ProClip yesterday.
Next week we will have the following three Holders for cable attachment available. You can place your own cable in the bottom of the Holder to make a dock/undock solution as long as your cable plug has the same design as the following plugs. See link to images below:
http://www.brodit.com/images/915168.jpg (For use with any cable plug with the same dimensions as the one in the picture)
http://www.brodit.com/images/915177.jpg (For use with any cable plug with the same dimensions as the one in the picture)
http://www.brodit.com/images/915193.jpg (For use with the Griffin PowerJolt and iTrip Auto OR the same plug as used with the Griffing cbles mentioned)