Updated: 2/10/09 10:07 EST - v1.4
There have been some excellent discussions of late regarding how to classify and explain the relationships between the many Cloud Computing models floating about.
The comments are working again. I've had 30-40 comments via email/twitter, so if something you wanted to communicate isn't addressed, fire away below in the comments!
In v1.4 I added the API layer above 'Applications' in the SaaS grouping. I split out "data, metadata and content" as three separate elements and added structured/unstructured to the right. I also separated the presentation layer into "modality and platform." Added some examples of layers to the very right.