The two most significant innovations which came out of the Architecture sessions are those two manifests. The application manifest is something built by the software vendor to actually define the needs of an application in a hosted environment. It contains information for Provisioning as well as information on how to monitor that application and what metering information is being used.
The platform manifest is a definition of hosting resources such as web servers, database servers etc. and their attributes like load-balanced, clustered etc.

These two plus a set of parameters can be merged together to generate a set of installation tasks.