[informatimago]

Phone processors are at least one order of magnitude more powerful than (usual) 100 MHz CPU, therefore it would be of no use.

Anything you would want to do with that external processor would be slower and more inconvenient than doing it on the phone processor itself.

[alins]

Of course I know that. The question is whether there are applications for which an external, physically separated processor, even if weak, would be useful.