Python web development - with or without a framework
Django makes it possible to whip out a website rapidly, that's for sure. You don't need to be a Python master to use it, and since it's very pythonic in it's design, and there is not really any "magic" going on, it will help you learn Python along the way.
Start with the examples, check out some django screencasts from TwiD and you'll be on your way.
Start slow, tweaking the admin, and playing with it via shell is the way to start. Once you have a handle on the ORM and get how things work, start building the real stuff!
The framework isn't going to cause any performance problems, like S. Lott said, it's code you don't have to maintain, and that's the best kind.
I am planning on porting a PHP application over to Python.  The application is mostly about data collection and processing.  The main application runs as a stand alone command line application.  There is a web interface to the application which is basically a very light weight reporting interface.  
I did not use a framework in the PHP version, but being new to Python, I am wondering if it would be advantageous to use something like Django or at the very least Genshi.  The caveat is I do not want my application distribution to be overwhelmed by the framework parts I would need to distribute with the application.  
Is using only the cgi import in Python the best way to go in this circumstance?  I would tend to think a framework is too much overhead, but perhaps I'm not thinking in a very "python" way about them.  What suggestions do you have in this scenario?