Determine the earliest version you'll support.
"Even with third-party security tools in place, one of the biggest challenges administrators face when managing Android is that they can't have sweeping policies that cover each and every OS version," says Forrester's Christian Kane.
The same is true for iPhone. The way around this is to set a baseline that your organization will not go below. For Android, 2.2 should be the cut-off, while iPhones below iOS 4 should be stuck outside the corporate gate.