I discovered this small ncurses based tool just yesterday… Just start it as root and it will spit out info on how often the CPU must return from C3 sleep mode to a more power consuming mode, and what the reasons are. It will also show various hints on how to reduce power consumption on your system. The tool is intended for computers with Intel mobile CPUs. It’s available through portage (sys-power/powertop).
Nice work, Intel!