In current mobile phones, what are some specific techniques that prevent handling noise (rubbing, jostling) from being picked up by the microphone?
The microphones are generally mechanically decoupled from the housing.
If the mic is in the housing then it is usually in a soft rubber boot that reduces noise from carrying over.
If the mic is on the board, then there's already decoupling from all the mechanical barriers (noises have to go from the housing to the PCB to the mic, and there are losses at each stage.)