An association's meeting planning staff and committee chairs can then invite users to participate in a video, voice, text chat and screen-sharing web conference. It is far from perfect today but already very popular. It is an attractive alternative to high-priced web conferencing. Give it two or three months and it will be smoother to use.
Two other "group work" services are Thinkature (for online collaboration) and Conceptshare (for the group creating the online and print promotion for the meeting.
If anyone's using these tools, I'd be curious to know what you think of them.