Yahoo said that it recently <A HREF="http://www.eweek.com/article2/0,1895,1913230,00.asp">turned over information</A> about its users searching habits to federal investigators, a startling admission that has touched off a new round of privacy concerns. As previously reported, search inquiries may be evidence in an upcoming trial that the government hopes will revive a controversial 1998 Internet law to protect children from stumbling onto inappropriate material on the Web. The law was struck down two years ago. The search queries are to serve as the raw material so the government can test whether Web filters are a match for the overwhelming amount of pornography that a child could run into while online.