Yes.......We always use our room key as a charge card. It makes things very easy during your stay.
When you check in you will be asked if you want to do this. The Cast Member at your front desk will then link your room key to any major credit card you want to use. You can charge away at just about everyplace in WDW. A number of the carts in the park now accept charging but not all have telephone connections yet. You can get a print out anytime from the front desk showing the details of your charges. At check out they give you a complete listing.
They only charge your credit card once you reach the resort maximum and then you start over at zero. For values it's $500.00, mods have a $1,000 limit and deluxes have $1,500 limit.
Very convenient and let's you carry very little cash around.