I just tested on Python 3.2, and found something interesting; it seems a ^Z character on a line that has other input read in as a character.  Also, other input after an EOF on its own means you still have to do two more EOFs to end.

Python 3.2.3 (default, Apr 11 2012, 07:15:24) [MSC v.1500 32 bit (Intel)] on win
32
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>>> import fileinput
>>> lines = list(fileinput.input())
test
testing
^Z
^Z
>>> lines
['test\n', 'testing\n']
>>> lines = list(fileinput.input())
test
testing^Z
^Z
^Z
>>> lines
['test\n', 'testing\x1a\n']
>>> lines = list(fileinput.input())
testing^Z
test
^Z
testing
^Z
^Z
>>> lines
['testing\x1a\n', 'test\n', 'testing\n']

Also, the documentation for fileinput doesn't mention EOF at all.