Lately I've built some really neat forms where the controls are moved based on the size of the form or in response to use input. It's not so hard to change the position of a control and it can make for a really well optimized user interface.
One of the particular challenges when moving controls is keeping the controls on a tab control in their proper place. If you move a tab control the controls on the tabs don't move on their own. A.D. Tejpal recently posted this sample database on Rogers Access Library that demonstrates enumerating the controls on each page of the tab control and moving them all so that they all stay together and stay in the right place on the tab control.