Not so much "retired," that is. The US government has just reserved the right to call you back after retirement, indefinitely if it decides to. And by swearing up and down it won't cost much to do this, they were able to bypass the approval processes of something like eight different agencies which would normally be involved.

Take a gander at this, from Cryptome:

Management and Mobilization of Regular and Reserve Retired Military Members

AGENCY: [U.S.] Department of Defense.

ACTION: Interim final rule…
 

Sec.  64.4  Policy.

    (a) It is DoD policy that military retirees be ordered to active duty as needed to perform such duties as the Secretary concerned considers necessary in the interests of national defense as described in 10 U.S.C. 12301 and 688.
    (b) The DoD Components and the Commandant of the U.S. Coast Guard shall plan to use as many retirees as necessary to meet national security needs.
    (c) The military retirees ordered to active duty may be used according to guidance prescribed by the Secretary concerned as follows:
    (1) To fill shortages or to augment deployed or deploying units and activities or units in the Continental United States, Alaska, and Hawaii supporting deployed units.
    (2) To release other military members for deployment overseas.
    (3) Subject to the limitations of 10 U.S.C. 973, Federal civilian workforce shortages in the Department of Defense, the U.S. Coast Guard,
or other Government entities.
    (4) To meet national security needs in organizations outside the Department of Defense with Defense-related missions, if the detail
outside the Department of Defense is approved according to DoD Directive 1000.17.\2\
    (5) To perform other duties that the Secretary concerned considers necessary in the interests of national defense.
    (d) Military retirees shall be ordered to active duty with full pay and allowances. They may not be used to fill mobilization billets in a non-pay status.
    (e) Military retirees serving on active duty may be reassigned to meet the needs of the Military Service.

But wait! There is, of course, a feedback process. There's no guarantee whatsoever that they will read, much less respond to your feedback, but you are cordially invited to tell them what you think of this policy of geriatric zombie soldier resurrection. At least they promise to pay the geezers, so although it is involuntary labour, it's not techically slavery. Until someone decides to bill them for room and board…wait for it:

DATES: This rule is effective April 18, 2006. Comments must be received
by June 19, 2006.

ADDRESSES: You may submit comments, identified by docket number and/or
RIN number and title, by any of the following methods:
    Federal eRulemaking Portal: http://www.regulations.gov.

Follow the instructions for submitting comments.
    Mail: Federal Docket Management System Office, 1160
Defense Pentagon, Washington, DC 20301-1160.
    Instructions: All submissions received must include the agency name
and docket number or Regulatory Information Number (RIN) for this
Federal Register document. The general policy for comments and other
submissions from members of the public is to make these submissions
available for public viewing on the Internet at http://regulations.gov

as they are received without change, including any personal identifiers
or contact information.

FOR FURTHER INFORMATION CONTACT: Daniel Kohner, 703-693-7479,
Dan.Kohner@osd.mil.