Greg Wilson has grumbled about the lack of a Python response to Ruby on Rails before, and I didn't find his arguments compelling then either. Ruby on Rails was the right tool at the right time--at least a good tool. It didn't become popular because a committee or dictator decided it would be popular. It became popular because people liked it. You can't decide to make a specific Python tool popular by fiat.
I've read a few good blog posts on the subject. Christopher Lenz makes some credible criticisms of Django. The problems he describe sound like the sorts of problems that Zope ran into years ago. Using Python as your configuration language? Yikes. (Almost was bad as using ZCML <0.5>.) Speaking of Zope, cguardia asks why Zope doesn't count in Greg's list of web frameworks. Ian Bicking has a better explanation of the problem.
Ian's comment on Greg's blog: Getting a good story together for new users is important. That story probably should not start with “analyzing what framework is best for you.”Regardless of who the winner is or why you would care, the Django team should make sure it understands the lessons Zope did learn about de-coupling components, configuration, and separating policy and mechanism. Update: Adrian Holovaty address my concerns in one of the comments. They make not like Zope's solutions to these problems, but Lenz's post made me wonder if they appreciated the problems yet.