Security on Mobile Devices:State of the Art,Open Problems,Proposed Solutions [pdf]

This is a good overview on the current state of security on mobile devices (mainly iPhone and Android devices). I'd recommend that smartphone users who have more than just a casual interest in smartphone security download or read it.

I'd particularly recommend the paper to Android users who've root their phones or those who develop tools for rooted phones. Whilst you're unlikely to gain any additional insight into the specifics of rooting any phone from the paper, you will get a good overview of how unlocked bootloaders/rooted phones fit into the grand schema of Android security (i.e.: how Google, phone and app manufactures deal with security including matters relating to the SafetyNet issue, electronic fuse trips, etc.). Essentially, discussion isn't at a nuts-and-bolts level but rather how these techniques are viewed from a security/policy level.