This document defines a set of major usage scenarios
for collaborative environments along with typical
implementation approaches.  The security issues
and threat scenarios for these implementations
are then discussed in great detail.  The document
concludes with some discussion of the performance
implications that security may have on the
quality of experience for collaborative systems.

Besides documenting these issues (which is important
and useful) this document also points to some
more joint work with the security area, e.g., mapping
out concrete uses of grid security mechanisms to
address these issues in collaborative environments.

I think this document is ready for publication.