Alter the profiler to capture nscanned for count() just like it would if it was a straight query.

in 1.8.1:

{ "ts" : ISODate("2011-07-18T22:32:47.256Z"), "info" : "query platform_addressbook.$cmd ntoreturn:1 command: { count: \"contact\", query:

{ userId: \"000044607693\", groups: \"test-group\" }

} reslen:64 30ms", "millis" : 30 }

Would like it to be:
{ "ts" : ISODate("2011-07-18T22:32:47.256Z"), "info" : "query platform_addressbook.$cmd reslen:2082 nscanned:292026 ntoreturn:1 command: { count: \"contact\", query:

{ userId: \"000044607693\", groups: \"test-group\" }

} reslen:64 30ms", "millis" : 30 }