According to WDW News Today, Disney is testing the concept of paid parking for non-resort guests at Walt Disney World. The testing was recently done at Disney’s Contemporary Resort and a new testing period will being soon at Disney’s Boardwalk. The test is the latest attempt by Disney to control parking at the resorts. This step is needed so that guests can not use parking at the resorts to visit the theme parks rather then pay the daily rate at the parks. Under the possible new policy, guests without a resort reservation at the resort they are attempting to park at or a WDW resort guest, would be required to pay a parking fee in order to park at the resort. Paid parking would not apply to those with dining reservations or Tables in Wonderland members (who get free valet when dining at a resort restaurant).
I have not seen anything that indicates what the resort parking fee is but I assume it may be in the same range as the fee charged at the parks (or more if they really want to stop the practice).