"Ms." arrived in 1980. "Illegal immigrant" entered in 2004 (and left this year). The hyphen in "e-mail" left the building in March 2011.
Zach Dyer catalogs these and other changes to the AP Stylebook since 1980 in a nifty interactive timeline. The news collective's process for changing style is "fairly democratic," he reports after a conversation with AP Deputy Standards Editor David Minthorn:
For a more controversial term, like “illegal immigrant,” Minthorn said the organization considered feedback from its editors, some of who cover immigration, and took a vote. “It wasn’t unanimous but there was a strong majority,” he observed.(more...)