iPhone 4s Power Cable Compatibility
Can I use an iPhone 4s power cable to charge any other mobile device?


Short answer...YES you can

The cable is Apple's (legacy) 30 pin connector.



This cable is compatible with 


iPhone 3G through 4s
iPad 1st through 3rd Generation
iPod (various generations)


Apple has a complete and official list of supported devices on their product page: Apple 30-pin to USB Cable