Well, for the WSS application developer exam, you’re supposed to know about programmatically checking in and out documents:

//*** Check out a document
Console.WriteLine("Check out {0}", myItem["Name"]);
myItem.File.CheckOut();
Console.ReadLine();
//*** Check in a Document (Minor Check in)
myItem.File.CheckIn("Checked in Programmatically", SPCheckinType.MinorCheckIn );
Console.WriteLine("Item Checked in");
Console.ReadLine();

One should also be able to list all versions of a document:

//*** List all versions of a document
Console.WriteLine(myItem.Name);
foreach (SPFileVersion ver in myItem.File.Versions)
{
Console.WriteLine(" - v{0} ({1})", ver.VersionLabel, ver.CheckInComment);
}
Console.ReadLine();

And restore a version:

//*** Restore to version 1.0
myItem.File.CheckOut();
myItem.File.Versions.RestoreByLabel("1.0");
myItem.File.CheckIn("Restored by Program to v1.0");
Console.WriteLine("{0} restored to v1.0", myItem.Name);

All pretty straight forward.