How to see which CPU is on the current machine?
From terminal, you'll want to start with system_profiler
system_profiler SPHardwareDataType
Also, much more data is available from ioreg but you'll need to parse the output (which can arrive as XML if you prefer) to get things like actual bus and clock frequency of each core.
On the other hand, if you don't want processor name, speed, the number of processors, etc but you're interested in the model number, you might want to give sysctl -n machdep.cpu.brand_string a try, eg.
$ sysctl -n machdep.cpu.brand_string
Intel(R) Core(TM)2 Duo CPU E7600 @ 3.06GHz