According to the email thread starting:

http://mail.python.org/pipermail/python-dev/2003-
October/039081.html

the control variable name in a list comprehension should 
not be leaked and any use of such a leaked name is 
deprecated.

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Ref Man 5.2.4 List displays:  suggested addition at end.

Using leaked 'for <exp_list>' control variables outside the list 
display is deprecated and will not work when the bug is fixed.

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A good point raised by Michael Hudson is that

   foo = [x for x in R]
   print x

will fail if R is empty (and x wasn't previously defined).
All the more reason to deprecate its usage and 
suppress the leaking variable.

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Actually, this is not different from
$ python
Python 2.4a0 (#2, Oct 14 2003, 11:28:48)
[GCC 3.2.2 20030222 (Red Hat Linux 3.2.2-5)] on linux2
Type "help", "copyright", "credits" or "license" for more
information.
>>> for x in []:
...     pass
...
>>> print x
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
NameError: name 'x' is not defined
>>>

where x is also undefined after iteraring through an empty list.

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The tutorial will also need revision of deletion:
5.1.4 List Comprehensions
has this:

To make list comprehensions match the behavior of for loops, 
assignments to the loop variable remain visible outside of the 
comprehension: 


>>> x = 100                     # this gets overwritten
>>> [x**3 for x in range(5)]
[0, 1, 8, 27, 64]
>>> x                           # the final value for range(5)
4

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I notice that the tutorial currently in CVS seems to have been already fixed (by exciding the paragraph tjreedy quoted).  To fix the reference manual, I propose the enclosed patch.

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I've applied Alex's suggested patch.  Thanks, everyone.