I seem to remember there being something weird about the twisted that ships with 10.5 (which itself ships with python 2.5)
e.g. as far as python is concerned 'twisted' is already installed as v 2.5.0
#[Thu Jun 19 17:15:49] otto:~$ echo $PATH
~/Library/bin:/usr/local/bin:/usr/local/bin:/bin:/sbin:/usr/bin:/usr/sbin
#[Thu Jun 19 17:15:52] otto:~$ python
Python 2.5.1 (r251:54863, Apr 15 2008, 22:57:26)
[GCC 4.0.1 (Apple Inc. build 5465)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import twisted
>>> from twisted.copyright import version
>>> version
'2.5.0'
>>> ^D
otoh, the notes in #229 suggest asking pkg_resources, which reports 2.4.0
#[Thu Jun 19 17:16:34] otto:~$ python -c 'import pkg_resources;print pkg_resources.require("twisted")'
[Twisted 2.4.0 (/System/Library/Frameworks/Python.framework/Versions/2.5/Extras/lib/python)]
neither of which goes any obvious way to explaining why setuptools requirement on 'twisted>=2.4.0' caused it to try and find 2.5.0 to install, given that 2.5.0 is not available in any of the places it looks.
I'm going to try installing the 8.0.1 .pkg installer from the twisted web site.
