Almost any electronic device can be hacked or infected with malware, if an attacker has reason to target it. In practice, whether your device becomes a choice target usually depends on popularity and accessibility. When products such as Amazon's Kindle and Kindle Fire establish a large new market niche, it's only a matter of time before someone finds a way to exploit it. If you use Kindles, it's prudent to protect them -- and through them, your network -- from potential attack.