As the numbers of Android running devices coming to the market keeps increasing, Google recently launched the Android Enterprise Recommended program. The purpose of the program is to help businesses make a better decision when searching for new enterprise devices.
Ruggedness specs should include, as a minimum, what kind of fall a device can survive while it's on, what temperature range it can reliably operate in, how well protected it is against dust and liquids, how much vibration it can handle.