I've found this question answered for C# and Perl, but not in the native interface. I thought this would work:

db.theColl.find( { _id: ObjectId("4ecbe7f9e8c1c9092c000027") } )

The query returned no results. I found the 4ecbe7f9e8c1c9092c000027 by doing db.theColl.find() and grabbing an ObjectId. There are several thousand objects in that collection.

I've read all the pages that I could find on the mongodb.org website and didn't find it. Is this just a strange thing to do? It seems pretty normal to me.