substituting vegetable oil for butter or shortening

Hi folks,

I've had good success substituting Canola oil for the Crisco shortening I used to put into my bread. Now I'm wondering about other baked goods.

Has anyone else tried making a substitution, particularly in a quick break like corn bread or muffins? If the recipe originally called for butter or shortening, are the general guidelines for making a switch?

Thanks for your advice.

Ann