So it turns out this situation is a bit more complicated than we first grasped. Teachers' home addresses aren't public information because they're public employees, per se. Rather, according to Pennsylvania's Right to Know law, everyone's home address is public information if it's on a public document somewhere. If someone requests that document, the information will not be redacted (Pennsylvania is one of the few states where this is the case).
There are three exceptions to this: The addresses of law enforcement officers, judges, and minors cannot be disclosed.
Of course, this leaves teachers' home addresses as ... public information, because their addresses are on file with their districts (a district is allowed to decline a request for the information if it believes giving it out would create a personal safety risk). Senate Majority Leader Dominic Pileggi has proposed legislation that would update the state's two-year old Right-to-Know law, but there's nothing in the proposal that would change the status of home addresses, according to Kim de Bourbon of the Pennsylvania Freedom of Information Coalition.
In any case, this issue is not so much about what information gets disclosed about public employees as it is about what information gets disclosed about everyone, and who should be exempt.