Let me also supplement the comments:
Skype is for only on-line communication. If both parties are on-line, then it is fine to use, but you are right, a personal discussion is much better. That is the moment when SyD is worth to use (or when they don’t have time to meet, but there are questions to clarify). As architect open up the computer and start documenting the building model, add comment to any details that might have questions, needs clarification. Every decision or ongoing issue can easily be added to any drawing element. Later on both the architect and client can watch it, comment it and review it in an ordered way. All the discussions can easily be reached with their history, so there won’t be any opened question or misunderstood concept. You can easily find still opened and already closed topics.
The example with Google Wave is also a very good idea. The only two problems of Google Wave was that it was not focused, you could have many unordered discussions about anything, so that it is not the right way of doing a serious, focused discussion on the planning or construction phase of a building.
The second one - Krippahl also mentioned - it doesn’t work from ArchiCAD. The screen capture could be made on Mac or Windows simply, but that screen capture doesn’t connect to any BIM model element. You even can’t status the particular Message Board in Google Wave (I think they were named “waves”), so it’s not easy to filter on ongoing issues in a particular BIM model (let us imagine that as a successful Architect you have more ongoing projects).
So as a result I would say Skype is a very good tool as well as Google Wave was too, but none of them can be compared to SyD that is a focused application to help the collaboration of architects using ArchiCAD with their clients.
