Thank you. My impression of Zope in the past has been that it does what I need, along with 10,000 other things I don't (built in WebDAV server?!), but clearly I owe it another chance. I've been initially attracted to mod_python because of its raw simplicity and its apparent similarity to mod_php and mod_perl, which I am familiar with. I'll give Zope a try.
Personally, I'd have to say that your impression was right. Once you start using Zope, you'll start to feel locked in. Sure, it does a lot for you, but it's also a big investment.
I can't really help you to get mod_python working on OS X, but concerning your other two points, did you notice these two sections in the documentation?
http://modpython.org/live/current/doc-html/pyapi-sess.html
http://modpython.org/live/current/doc-html/pyapi-mprequest.html
mod_python and Zope are not your only options by far. In fact, they're at completely opposite ends of the spectrum; mod_python being low-level in that you are in control of everything and have the necessary tools to build a framework, and Zope being the highest-level in that it does tons of stuff for you. There are dozens of frameworks in between.
If you do manage to get mod_python working, I suggest taking a look at Vampire as well: http://www.dscpl.com.au/projects/vampire/
I have had good experience with it. Once you start using mod_python you'll realize you can really go anywhere you want; and that's not necessarily a good thing. Vampire points you in a nice direction (I don't want to say 'the right' direction).
-- Brian Beck Adventurer of the First Order -- http://mail.python.org/mailman/listinfo/python-list
