It’s quite interesting.
Definition from White House Web site (Dec 2008):
“White House Military Social Aides serve as an extension of the President and Mrs. Bush in their roles as official host and hostess of the United States. They help to ensure guests have an enjoyable experience at the White House by assisting with introductions to the President and Mrs. Bush during receiving lines, the guests’ seating, and the overall flow of events. The program averages 40 Social Aides from all five military services.”
And one former aide wrote a book about his experiences.