Well. To be fair I doubt this data is actively used to snoop on someone. Most companies uses personal data for statistics and such. (Social internet sites and smartphones are gold for data miners. Most of the time they don't ask for permission.)
However, the extent of location data being stored is alarming. And being stored on a file means it's easy to access for anyone.
A higher-up at Apple *cough*Steve Jobs*cough* could for example deliberately access the Iphone of a competitor and look for ways to blackmail him. or he could blackmail politicians or judges.
Apple detects you are using a hacked iphone. They sue you for breaching the DMCA and they got your location so you can't run. Oh, and they also brick your phone for good measure.
If you are involved in some legal issue. Police can confiscate your Iphone and they will have detailed information about your movements for an extended period. Even if you were innocent, perhaps the investigation will reveal you were cheating on your wife.
They sell your personal info to spammers. Sinec they also got your location, they also sell this info to a airplane pilot whose job is to drop great offers on you from above.
The prime minister in my country is an avid ipad user. If for example the US wants him dead, they could just go via apple to get his location and smartbomb his ass. (ok, far fetched, but nevertheless possible)
"If you have specific questions ... don't hesitate to ask as the more generic the question is the more philosophic the answer will be" - PSPWizard