@trouble- I don't have any personal experience or insight in this matter. I just looked it up. The 5 points are from http://travel.state.gov/visa/temp/info/info_1288.html.

* No Objection Statement (NOS):

The EV's home country government issue a No Objection Statement (NOS) through its Embassy in Washington, DC directly to the Waiver Review Division that it has no objection to the EV not returning to the home country to satisfy the INA 212(e) two-year foreign residence requirement and does not object to the possibility of the EV becoming a resident of the U.S. The NOS may also be issued by a designated ministry of the EV's home government and forwarded to the U.S. Chief of Mission, Consular Section, within that country to be forwarded directly to the Waiver Review Division. The EV has the responsibility for obtaining a no objection statement from his/her home government.