There's nothing quite like shaking someone's hand, conducting a face-to-face meeting, and then heading out for lunch together. But when multiple people, travel costs, and packed schedules are involved, sometimes videoconferencing is an attractive alternative.

During the Meeting
Introduce everyone: If the participants don't know each other, have them introduce themselves. Consider setting up nameplates if there are multiple people who haven't met before.
Act normal: Look straight into the camera, speak like you normally would, and use natural gestures.
Don't be distracted: Checking your Blackberry every couple minutes or looking around the room can distract other participants. Focus on the meeting and don't try to get other work done.
Avoid side conversations: If you absolutely have to discuss something privately, mute your speaker. Address any anticipated issues with members of your office before the conference.
Limit your movement: If you're speaking, try not to use big gestures. These may disrupt the picture transmission and cause delays in everyone's communication.

Don't wear distracting clothing: This doesn't mean that you have to wear gray, but avoid bright colors, busy prints, and large, shiny pieces of jewelry. In other words, no videoconferences on Hawaiian Shirt Day.
Don't talk over each other: Keep in mind that there could be a delay; if it seems to take someone a few seconds to respond, be patient. Set up rules for speaking, if appropriate.

Don't bring food into the meeting: Eating is just one more potential distraction and won't be appreciated by hungry participants.