Interesting read indeed, but I think still largely redundant. If there are malicious apps out there, they likely got there from installing unknown sources apps or sideloaded apps. As far as an actual virus like one you might get from an e-mail, to my knowledge, we have yet to see one. While I think there will come a time for these anti-virus, firewall, etc. programs, I'm not going to panic and waste my app space for this stuff right now.