Here’s a nice little blurb from Tech4Learning about cross platform (Mac to PC) desktop videoconferencing.
Another option the teachers could pursue is using the commercial software Trillian Pro on the Windows-side. Users of Trillian Pro can videoconference directly with Macintosh users running iChat AV videoconferencing software.
Did you know that? It was new to me. If anyone has tried this, please leave a comment as to how well it works.