The new client for iPhone will leverage WiFi and 3G connections. I would hate to see it over an Edge connection though. The application will be free from the App Store and will support audio, texting in a messenger like method and the ability to view content shared from other attendee's desktops. As of the current release video is not supported.
Read more here.
Taking advantage of the 3G and WiFi abilities in the latest generation of iPhone, the Cisco WebEx Meeting Center for iPhone will be available as a free download. In addition to the ability to participate in WebEx meetings, users will have the ability to exchange instant messages as well as view content that is on other meeting attendee computers, provided that they are sharing their desktop or presenting. Currently, video is not supported.
The ability to use your iPhone as a conduit to attend WebEx meetings on the go is a great offering for the iPhone to offer. We have to wonder, however, if being able to attend meetings on the go is really a good thing.