Any form of digital communication can be pedophile/rapist/whatever bait; developers try for a bit but can never prevent it completely.
Besides the obvious, the main thing is to raise awareness. If your child doesn't know about (or you don't want to crap on their worldview by burdening them with) pedophilia or stuff, give other reasons why it's a bad idea to share (real) personal information. I've seen pretty smart kids do pretty stupid things because they thought they "knew" the other person. I don't know your child's age, which also sort of determines a lot of things. You can lock a 6 year old out of a lot of stuff (or keep them in the dark) much more than a 12 year old.
Having sat through my fair share of e-crime lectures and meetings (because of my job, not court mandated to be there, natch
), the main thing to remember is that some people are willing to go very, very far to convince others. Being on line friends with someone for 3 or 4 months seems like an eternity to children or teens, but it's all set-up; the other may volunteer to share pictures first (because it's so hard to fake a picture... but it looks so real!), share stories/feelings/"really personal" stuff first. Most parents still seem to think predators like a "quick kill", talking/chatting a few times and then pushing forward, while the reality is these days most successful ones are slow stalkers who wait 'till trust is gained.
No matter who or what the other claims to be, unless it's someone you know IRL, it's usually a good idea to be skeptical. It may come as a shock to some, but I'm not, in reality, an owl, for example.