Ben Askins and Alan Green saved me the trouble.
Their presentation (which requires the latest Flash plugin) is a decent, balanced summary of the similarities and differences between the two frameworks. It’s 100 pages, but is paced for speed (and it’s a fine model for how to do compare/contrast presentations).
The only bit I’d add is that Django favors parallel development to a greater extent than Rails. With Django, you get to a clean separation between code and templates sooner, so that UI designers can be working on presentation while coding continues. And Django’s out-of-the-box admin interface supports lets people start doing data entry pretty much as soon as you’ve built your data models. Django doesn’t yet have migrations, though, so there’s more emphasis on getting your data model right up front.
If you’ve already chosen one of these frameworks, it may be worth your time to check out the other. There are good ideas in both.