As of lately, I experience the same image problem that plagued WordPress.com some months back
In short, what happen is that image that hosted on the service from one post (the issue does not affect those image using external service eg Flickr. Only those image that are stored using WordPress.com ) end-up replacing another in another post. Worse is that the original image cannot be reverted back by WordPress.com but only by user tediously doing the replacement in each affected post (Provided that he know which post is affected).
As can be seen from the following post, images have been randomly replaced in the post.
One of the posts affected are
As can be seen, the images of recent post replace those of other post for no apparent reason.
It looks like other users are experiencing the same frustration. Forum => Photo changes
Urge others not to create or update post that contains images hosted on WordPress.com until the problem is ‘officially’ resolved. As of current, the case is still opened.
I will not be rectifying any image screwup in affected posts in the meantime.