I can't express how saddened I am by this outcome. It's a dreadful shame and I feel for her friends and family. What really annoys me about this story though are the people commenting that she was naive, stupid, foolish, that she somehow 'had it coming' because she was hitching alone in conspicuous clothing, and that the outcome somehow proves that, a. people (and men in particular) are inherently evil, and b. hitchhiking is suicidally dangerous.
I've never hitchhiked. This has far more to do with a persistent worry that nobody would stop for me than that I might be picked up by a maniac. I have picked hitchers up several times and will happily do it again. I would do so more often if they weren't such a rare sight in this country, I suspect largely due to media sensationalism; the very rare incidents of violence against hitchers being far more newsworthy than stories of people successfully travelling the world, meeting new people and conserving resources. Obviously you need to exercise a bit of common sense before picking someone up or accepting a lift - take a look at the hitcher/driver, ask them where they are going, and say 'no' if something feels wrong. If you're sensible, I really don't think it's significantly more dangerous than other situations where you come into contact with strangers (eg. travelling on public transport).
Pippa Bacca's story is inspirational. Not because of how her life ended, but because she believed in the inherent humanity and kindness of people everywhere. I hope her message will live on and not be tarnished by those who feed on misery and take every opportunity to shout, "I told you so!"