The Chronicle of Higher Education had a lengthy article this year on use of the "gap year" to gain acceptance to an elite college.
It works like this: A high school senior is rejected from the elite schools she has set her heart on and only accepted at Second Choice U. She gets a deferral from Second Choice U so she can spend the year after high school pursuing an unusual academic interest, community service, or travel. She also reapplies with this additional experience under her belt to the School of her Dreams. If she gets accepted to School of her Dreams all is well. If not she goes to Second Choice U having had a great experience during her gap year.
School have different reactions to students playing this game. Some say it is a legitimate use of the gap year, simply a reflection of increased growth and genuine maturation. Others feel it is unethical to defer, promise to attend, and then skip town.
In any case, you can expect that the non-refundable deposit required for those seeking deferrals is going to become quite steep.