The following input (with a blank line) works in mongo shell prior to 2.0:

C:\mongodb\mongodb-win32-x86_64-1.8.2\bin>mongo
MongoDB shell version: 1.8.2
connecting to: test
> var doc =

{ ... a:1, ... ... b:2 ... }

> doc

{ "a" : 1, "b" : 2 }

>

But no longer works in mongo shell 2.0:

C:\mongodb\mongodb-win32-x86_64-2.0.0\bin>mongo
MongoDB shell version: 2.0.0
connecting to: test
> var doc =

{ ... a:1, ... ... b:2 > }

Tue Sep 20 12:59:57 SyntaxError: syntax error (shell):1
> doc
Tue Sep 20 12:59:59 ReferenceError: doc is not defined (shell):1
>