NIST Cloud Computing Reference Architecture

I'll have to dig into these 26 pages.  NIST continues with their useful work addressing cloud definition, categorization, and architecture.

Collaboration site here: http://collaborate.nist.gov/twiki-cloud-computing/bin/view/CloudComputing/WebHome

Reference Architecture (PDF) here:
http://collaborate.nist.gov/twiki-cloud-computing/pub/CloudComputing/Meeting12AReferenceArchitectureMarch282011/NIST_CCRATWG_029.pdf