mDNS security
Recently on The Register: Apple Response To Worm Threat
This is what got me involved: Roughly Drafted: A Global Upgrade for Bonjour (mDNS)
I wrote a response to that blog post:
Security Concerns with Internet Wide Self-Advertising Services
Essentially, having Bonjour working across the entire internet is a terrible idea, and would lead to threats like Rape.OSX being able to run rampant across networks and the internet at large.