All you peeps with kids should get this
Zoombak™ Advanced GPS Dog Locator
http://www.zoombak.com/products/pet/
It keeps tracks of your pets or assets (children). They need to make one with a titanium case, tamper alarm, and a titanium cold-pressed lock and shackle too.
It supports virtual fencing which is about the coolest damn thing about GPS ever.

Comments
Once the munchkin figures out walking (and thus running), I can see the need for GPS homing/tracking, though hopefully she never gets far enough out of my sight for that.