GPS tracker recovers stolen property
Not specifically about bicycles, and the GPS used is not mentioned, but it does prove GPS trackers can recover stolen property, so it could work for a bicycle.
GPS tracking device leads police to men suspected of breaking into homes in Rochester Hills, Troy
2000 Montague CX, I do not recommend it, but still ride it.
Strida 3, I recommend it for rides < 10mi wo steep hills.
2006 Rowbike 720 Sport, I recommend it as an exercise bike.
1996 Birdy, Recommend.
Wieleder CARiBIKE (folding), decent frame.