Here's what I've found so far after starting a small Django gig (I already knew a fair bit about Rails):
- Rails has built-in migration support
- Rails has better support for APIs
- Django has some neat stuff in contrib including authentication and an admin interface
- Django has "pluggables" -- downloadable apps that can be snapped in just like the admin interface. Rails has engines, but they're new and not as mature as pluggables.