The parent task was partially resolved: Images posted to topics with the [img] tag are now being resized based on the size of the post area. However there is another scenario to this that deals with images that are in a post that are resized as thumbnails.
When thumbnail creation is enabled for attachments the thumbnail is a link to the larger image. This will open right in the same window, which doesn't seem like a good user experience. Instead of doing this the attachment should be expanded via a lightbox-type window right on the same page.
This seems to be a highly requested feature and we should really look into implementing it.