Here is a start at the high level architecture for COSMOS.
Here are the COSMOS Use Cases we have documented so far.
Each of the major components has a wiki area at the following links:
To better understand and comment on how COSMOS relates to other projects look here Project Relationships
Work In Progress. Here's some initial discussion on the mailing list http://dev.eclipse.org/mhonarc/lists/cosmos-dev/msg00659.html