I did work for a company that gave every employee a blackberry, they were great for sending jobs to employees and also tracking them. Never knew it then but they have a tracking device in them.
Here is a clue for you, every phone made since the patriot act has a GPS on them... Every Nextel you can buy, lease, borrow or even steal has a GPS function and while there is a soft switch to turn it off, the owner of the account can turn it back on.