Snyder allegedly didn't intervene when students discussed drugs and drinking, administrators said. She had already been admonished to avoid corresponding with students on MySpace and conceded that a student had seen her Web site and that the cup in the picture contained alcohol, the school said.
"Millersville University is committed to serving our students and the children they will teach, and we are confident that the university will be vindicated in this case," the university said in a statement.
Most school districts are only beginning to consider official policies that specifically deal with sites like Facebook and MySpace, said Tom Hutton, a senior attorney with the National School Board Association.
"As a society, we're trying to deal with this on the fly," said John Green, head of school for the Peddie School, a New Jersey boarding school.
"Boundaries are important for teachers to maintain," he said. "The virtual world makes those boundaries more blurry. Sometimes people are less careful in maintaining boundaries over the computer than they are in their own classroom."
Teachers associations and some school district lawyers are warning new teachers to be careful what they put online.
Todd Fuller, of the Missouri State Teachers Association, said a school superintendent recently told him he asked aspiring teachers about their MySpace pages during job interviews.
"He had a teacher come in and asked her if she had a Facebook or MySpace page and she said yes, and he said would you be willing to have a look right now?" Fuller said. "If that would be an issue for you, you should take pause and consider what's on your page."
Credentialed teachers can generally be reprimanded for activity that disrupts the classroom in some way, said David Alexander, chairman of the Department of Educational Leadership at Virginia Tech.
Several teachers told ABC News that they restrict access to their Facebook and MySpace pages and would never allow their students to become their online friends.
"I worry about kids' ability to contextualize what they're seeing," said Alison Hogarth, who teaches ninth through 11th grade in New Jersey.
But other teachers have apparently not considered the consequences of their online behavior or aren't willing to change them.
Stephen Murmer was famously fired from his teaching job in Virginia after videos of him painting with his buttocks surfaced online. He settled a lawsuit against the school district last year.
Abby, a 23-year-old elementary school teacher in New York, described "excessive drinking" as a favorite activity on her Facebook page and had a "bumper sticker" that said "let's drink so much we hate ourselves in the morning."
As for Snyder, according to court papers, she wrote on her MySpace page that she was told "one of my students was on here looking at my page, which is fine. I have nothing to hide. I am over 21, and I don't say anything that will hurt me (in the long run). Plus, I don't think that they would stoop that low as to mess with my future. So, bring on the love!"
Eight days later, she was told she would be ineligible for a teaching certificate.