Hey Martin, I am not sure who removed the "modlook" tag from your thread. It might have happened by accident in the shuffle of WordPress.com breaking :(
It would really help if you could list the exact steps that you are taking so that we can try to test and reproduce.
If I do what you describe, here is what I get:
1. I check 3 images in the library.
2. I only see "Bulk Actions" and "Delete Permanently" under the dropdown.
3. If I leave the dropdown at "Bulk Actions" and then click "Apply", nothing happens and the images are no longer checked, which is what I expect. If I select "Delete Permanently" and click "Apply", it deletes the selected images, which is the expected behavior, too. There is no "Bulk Edit" option that you mention.
Perhaps you are attempting to bulk-attach several images to a post? If I select several images and then click on "Attach" next to one of them, then I have a dialogue pop up that allows me to search for a post or a page and then attach all the images there.
If you could list the exact steps I will be happy to reproduce again :)