According to MSDN, Microsoft.SPOT.Hardware.Cpu.SystemClock will return the cpu clock. On my Domino it returns 18000000 or 18 MHz yet it should be 72MHz :o am I missing something.

Maybe it shows the base clock without multiplicator?

18 MHz x 4 = 72 MHz

Peripherals run 18mhz to lower the power consumption but the CPU is going at 72mhz