GPS Track employee phones

You can't. Apps can't run in the background and any of the location apps would have to be left open. If someone calls or sends a text or using any app, the location is shut down.

Actually you can in enterprise, here's one solution:

http://www.air-watch.com/Solutions/iphone.html

You also need to consider the legality of that in your country - it sometimes can be illegal.

You would need to write your own configuration profiles, hire someone to do such for you or use off the shelf solutions. And, no, you can't use mobileme. But, you can do what you want and many enterprises do.

Air Watch is one of the better solutions because they insure you're in compliance with Sarbanes Oxley, PCI and HIPPA, automated security rotations, etc. and they've been around awhile. There are others out there, google would be your friend here.