Re: @AC 06:49 GMT
Open or closed source is insignificant, because an attacker does not make that distinction. A bigger concern is adoption scale. Consider the number of exploits that target Windows (closed source) vs. Linux (open).
A factor that contributes to Android's apparently vulnerable stack is that while Google make it mostly secure, you're risking the handset manufacturer as well as the network operator getting it wrong. And get it wrong they do with Android all the time. Not being able to uninstall apps that aren't wanted is a risk. Changing parts of the stock OS introduces risk.
I hate Apple in a really big way, but have to concede that their OS provides fewer opportunities for malicious or unintentional exploits, because Apple control the entire stack.