The New York Post reported this week that three New York City teachers are accused of inappropriate "friending" -- and worse. One teacher left comments like, "This is sexy," under girls' pictures, school officials told the paper. Others made lewder comments, and some even used Facebook to initiate real-life relationships with students, it said. All three have been fired.

New York holds no monopoly on disturbing stories involving teachers and social networks. In Pennsylvania, a teacher was suspended after students saw photos of her on Facebook posing with a stripper. In Florida, a teacher was suspended after posting a note saying he "hated" his students and his school. A Washington, D.C., special education teacher faced scrutiny after the phrase, "You're a retard, but I love you," was found on her personal page. In August, a 54-year-old math and science department supervisor was fired after she called her students "germ bags," on Facebook and described parents as snobby and arrogant. And news stories have chronicled the discoveries of photos showing teachers in compromising situations, striking sexual poses or drinking alcohol in glorified ways.

But the issue cuts both ways. In Colorado, students created a fake profile of a teacher and tried to portray him as a pedophile. Meanwhile, biting teacher parodies abound, and Facebook is littered with Web sites that publicly attack teachers and administrators.

Social networking is a digital minefield for school districts, adding to the already complex world of teacher-student relationships. Many districts are struggling to set workable policies around social networking, while at the same time, using Facebook and other similar tools as part of their educational program. How do they create virtual boundaries that protect teachers and students without squelching potentially useful technology tools?