These two queries return a different result (executed in the mongo shell):

> db.objects.find({ "_id" : { "$ne" : ObjectId("55dda2e17da396655548870b") } }).count()
139
> db.objects.find({ "_id" : { "$ne" : { "$oid" : "55dda2e17da396655548870b" } } }).count()
140

The first one is correct and the second - wrong - it also returns the object with that ID. Am I missing something or is this a bug?