Following from http://comments.gmane.org/gmane.comp.python.tutor/55576

>>> import subprocess
>>> subprocess.Popen(['a', 'b', 'c', 'd'], executable='echo')
<subprocess.Popen object at 0x7fdf7bb2bd50>
b c d

instead of the (what I) expected result
a b c d

I suggests two possible change:
1. add another optional argument called displayed_executable (or
something similar) and make the arg argument contains only arguments
2. it is made clear in the documentation that the first argument is used
as executable display name

Since the first alternative is behavioral change, it couldn't possibly
go through already released version; therefore if it is the chosen
solution it would have to go to Python 2.7 and Python 3.2. 

Changing the documentation should be easier, although the problem will
persist for unsuspecting users; and even if the first alternative is
taken, perhaps documentation change should still be done retrospectively
(I don't know the policy on doc change on old python version)

It should be noted that I tested this only with Python 2.5 on Gentoo
(although from the discussion, I presumed this is considered a feature
and would have persisted in later versions). And at the time of this
writing, I have no idea how it behaves in Windows.