At home it's on the kitchen counter plugged in to its charger, or next to me where I'm sitting if I'm expecting a call, or plugged into my laptop or desktop if I'm downloading music into it.
In work it's on my desk or if I leave my desk it's in my pocket.
In my car I have OEM integrated bluetooth so the phone is in cubby under the center armrest. I know you didn't ask about the car but I figured I'd throw in a little brag on the integrated bluetooth which I think should be mandatory in all cars and anyone using a hand held cellphone while driving should do 5 days in the clinker for 1st offense, more if repeat offender
I suppose if I turn on the "Location Services" and send a tweet all of you would know where my phone is! It's an iphone...I think other 3G and 4G phones also have Location Services.