This is not a bug or a syntax error, and the behaviour goes back to at least Python 1.5 if not older.

List.reverse returns a reference to the method object itself. List.reverse() *calls* the method. This is standard behaviour in Python, all methods and functions are first-class values, anything you can do with an object, you can do with a function or method too. For example:

py> list.reverse.__name__
'reverse'
py> print(len)
<built-in function len>
py> alist = [1, "a", chr]
py> print(alist)
[1, 'a', <built-in function chr>]