What is the *interrupting rating* of a GFCI receptacle?
I checked a few GFCI data sheets and they all listed either a 10kA Short Circuit Current Rating or Max Interrupting Capacity.


Leviton GFCI
Cooper Industries GFCI
Hubbell GFCI


I'm assuming that this is similar to the 10kA rating on common household circuit breakers where the device is required to break at least 10kA. 

Cooper Industries has a PDF that describes short-circuit current ratings in more deail:

Article 100 Definitions
Short-Circuit Current Rating. The prospective
symmetrical fault current at a nominal voltage to which an
apparatus or system is able to be connected without
sustaining damage exceeding defined acceptance criteria.