As one of the co-inventors of web conferencing, I find it mindboggling that after 20 years, the web conferencing industry continues to operate without any focus on standards whatsoever. Early attempts to standardize data conferencing around T.120 were never fully embraced, and it seems that web conferencing vendors today consider lack of interoperability a competitive advantage, used to lock in customers into their respective products.
The video conferencing industry, on the other hand, has taken standardization very seriously from the very beginning, and customers demand that equipment and software from different video vendors interoperate seamlessly. As video conferencing vendors have added more sophisticated data conferencing capabilities to their products, this too has been done in a standards-based and interoperable way (using the H.239 standard in the H.323 world, which is now being extended into the SIP domain).
Recent developments, however, are about to change the landscape. Web conferencing vendors have started to beef up the video capabilities in their products (e.g. HDFaces in Citrix GoToMeeting, High Quality Video in Webex, etc.), which will put these technologies in the cross hairs of IT professionals who manage video conferencing deployments. I believe that these video conferencing professionals will resist deploying islands of technology that don't interoperate, and will start putting pressure on the web conferencing industry to introduce open standards. These demands will extend beyond just voice and video, but will include standardization for data conferencing as well.
When this happens, video conferencing vendors will be in the driver's seat, given their long history of working in standards-based environments. Yes, web conferencing products are significantly more feature rich today than the Presentation Video alternatives in video conferencing systems, but it will be much easier for video conferencing vendors to catch up on features than it will be for web conferencing vendors to change their DNA and adapt to a world where interoperability and standards are key to survival.
Look for video conferencing vendors to take a big bite out of the web conferencing market over the next couple of years!