Once it's installed, there's no indication that anything else is running while the iPad is in use. It periodically uploads data silently to a private account for the installer to peruse at their leisure.
Mobile Spy claims this is designed to keep tabs on kids and employees, but let's be honest here: it's to keep tabs on your spouse you suspect of cheating or to stalk someone who's iPad you have access to.
Fortunately, it only works on jailbroken iPads, so the majority of people won't have to worry about this. But if you ever receive an iPad as a gift, make sure it comes in a sealed box if you in any way suspect the gifter of being a creep. [Mobile Spy via TechRadar]