videoconferencing & desktop sharing

We've been looking at systems for real-time videoconferencing, and even cross-platform desktop and app sharing. Here are some links:

• Marratech (commercial system).
  
• Elluminate (commercial system, cross-platform app sharing!)
  
• iVocalize (commercial, but inexpensive). It looks like a work-in-progress, but the TLT Group likes it and uses it.
  
• ePresence (open source, but I'm not sure if it works on Macs)
  
• and if you only have a few Mac people to talk with, iChat AV is amazing. Using Trillian I think you can even iChat with your PC colleagues.
  

In November, InternetWeek had a review of five web conferncing systems, and last month Network Computing had a good article "TechU: The World is Our Campus" where they graded nine web conferncing systems.