When we stayed at the Contemporary back in April 2009, it took us about 45 minutes. I believe we stopped at 2 other resorts before the Contemporary (otherwise it would have only taken 30-35 minutes).
But there are several factors that can affect how long it takes from the moment you step off the plane until the moment you reach your resort, such as:
-How long it takes you to get through the Magical Express check-in desk
-How long you have to wait for a Magical Express bus
-How long the bus waits for other parties
-How many stops the bus makes before your resort
-Time of day (traffic, etc.)
Generally speaking, most people make it to their resorts between 1-2 hours after stepping off the plane.