This is a comment on "growing up your acts_as_taggable" post on Evan Weaver's blog snax.... because comments there are closed.

If you are upgrading from an older acts_as_taggable installation and moving to has_many_polymorphs, as I did, your old table will have create_table :id => false. That will be unhappy. You should add this to your migration:

add_column :taggings, :id, :primary_key

And that's all.