Here are some helpful links:

Mashable - Hacker finds easy way to secretly save SnapChat pictures
BGR - Your Snapchats aren’t safe
NakedSecurity - Snapchat sexting spam
Bostinno - How to secretly save a SnapChat picture on your phone
Forbes - Snapchat - Why do kids love it and parents fear it?
Techcrunch - Snapchat experiences spammy growing pains
Gigaom - Users taking 150M images a day (before they disappear)
NYDailyNews - Facebook Poke app can't beat Snapchat