That's one of the most controversial problem in software engineering and several frameworks deal with schema evolution in different ways mostly through (as you've mentioned in your blog post) migration scripts.
Even though this is done through migrations in RoR, django folks decided not to deal with it as it's highly impossible to cater to different types of developers/admins. Here's a complimentary resource that you might want to look at:
http://code.djangoproject.com/wiki/SchemaEvolution
Edit: You just reminded me of a "Damn it!" moment i had, when i read the EF4.1 changelog and saw that default migration mechanism was not included.