On our current platforms you are limited to the characteristics of the CPU temp, fan speed) but not metrics (% idle, etc). There are platform limitations on v4.5.x that limit our ability to provide a meaningful number for CPU usage. The work that is being done is a mix between user mode processes and the kernel and all are not presented by the system in the same way.
With the next generation of our products (v9.0) we are introducing the concept of "red-lining" where customers will be able to determine when server load will be reached. v9.0 just went into beta and our scheduled ship date is this summer.
-Joe
Nimbostratus