Well, not exactly fired. Since Astronaut Lisa Nowak is still in the Navy and just on a "detail", NASA requested the Navy to reassign her. Space.com has the details on the detail.
Because she is a military officer, and not a civil servant, Nowak’s status falls under the jurisdiction of the U.S. Navy and is not subject to any administrative actions by the space agency, NASA officials said. Nowak will now shift to her next Navy assignment, NASA officials said.By the way, the accompanying photo shows Lisa holding an award from a group called NOIAW, the National Organization of Italian American Women. It seems Lisa was the First Italian-American Woman In Space. Not that there's anything wrong with that.
“She has orders, and she will be assigned to the staff of the chief of Naval Air Training in Corpus Christie, Texas effective March 21,” Commander Lydia Robertson, a U.S. Navy spokesperson, told SPACE.com.