In version 1.5, you can configure a certain selection of categories that will be applied to the post at expiration time. If you select expiration categories, this will override the default action of either changing the post status to draft or deleting it. If you leave all expiration categories unchecked, the default post action will be carried out as usual. When expiration time comes up, all categories on the post will be replaced with the new category selection set under the Post Expirator meta box.
In addition, on the Post Expirator setting page you can also choose to disable the category option and also set default categories that will be populated when you create a new post.
As you can see from the image above, the Post Expirator meta box code has also been cleaned up and moved over to the sidebar where it is more suited.
The plugin can be downloaded at the WordPress Plugins Page. Enjoy!