The python type() function for _id and binary types yield this (with a print):
myBlob <class 'bson.binary.Binary'>
_id <class 'bson.objectid.ObjectId'>

I am sure I am just a python newbie but what do I have to do to use

if isinstance(value, bson.objectid.ObjectId)

import pymongo doesn't seem to fulfill the namespace and I am admittedly a little Java-heavy so my head's not in the right place
P.S. isinstance(int) and long and datetime.datetime, etc. work great.