Hello ATG,
In the current version of SSM2007, the mission ends after you land and come to a stop on the runway. Although the mission is technically over at that point, the sim continues to run. To end the mission, you have to select "quit mission" from the menu. The "shutdown" procedures that the Command and Pilot perform after wheels stop in the real shuttle are not currently simulated in SSM2007. But, because the sim still runs after landing, you can perform them if you like.
Al