I don't know if it is only on V7 or if it will work in V6 too, but the latest version of the SIP firmware for the OpenStage 60 phone will allow you to plug one of a few supported webcams into the USB port and supposedly supports that camera functionality in one-on-one calls to other OS60 phones with webcams installed. Once you have the software and the cameras I know there are also some menu settings in the phone under features to enable the video as well.
I am planning on doing a trial with two of there to use as a doorphone to an attendant for customer service, but I haven't gotten around to buying the webcams yet.
For the "official" videoconferencing (on computers) we purchased OS Web Collaboration.