According to the Meteor documentation....
collection.insert(doc, [callback]) callback Function Optional. If prese
collection.insert(doc, [callback])
callback Function
Optional. If prese
This was a bug, fixed in the next release. Now, if you provide a callback to insert, it will be called with error and result arguments, where result is the ID of the new document, or null if there's an error.
insert
error
result