The AutoNav plugin now supports the tag and category taxonomies that this plugin creates. Once you go thru the AutoNav settings screens. you can for example use:
[autonav display="attached" postid="tag:chocolate"]
to display a gallery of all images, attached to the current post or page, and having the tag "chocolate" ... or you can even do:
[autonav display="attached" postid="-1,category:dessert"]
which will display a gallery of images in the "chocolate" attachment category, attached to any post or page.