Can you?..... you sure can if you want to....... Now I wouldn't recommend it. Apple tells in their iPhone info how and what to use to clean it.
From the iPhone User Guide:
*Keeping the Outside of iPhone Clean*
*To clean iPhone, unplug all cables and turn off iPhone (press and hold the Sleep/*
*Wake button, and then slide the onscreen slider). Then use a soft, slightly damp,*
*lint-free cloth. Avoid getting moisture in openings. Don’t use window cleaners,*
*household cleaners, aerosol sprays, solvents, alcohol, ammonia, or abrasives to*
*clean iPhone.*