Mobile Spy can be used to keep records of calls, SMS messages and visited web sites. The information is uploaded to a central server for access by the user.
The company is planning email and GPS logging in the future. It is only available for the second version of the iPhone, although the company states that the software isn't designed to need that phone's 3G connection.
The software isn't available from Apple's iTunes App Store, and so needs a jailbroken iPhone to work. This would make it difficult for an attacker to install on an unwitting user's iPhone, meaning that it will be more appropriate as a legitimate device for keeping records on company iPhones, or for potentially monitoring your own phone in the event of a theft.
It could potentially be employed by a devious user to keep tabs on an unwitting spouse, but the company has made it clear that it is not intended for unauthorised spying.