I'm in the process of moving multiple blogs into one big blog. In the course of importing all the blogs, I decided there were going to be several key content areas that have been assigned their own categories and I'm now in the process moving the already established categories into the new parent categories - it's time consuming. I've spent about 8 hours having to go in and touch each child category (except for those with sub-categories - those move all at once) that I want to move into the the new parent category.
It would have saved me a great deal of time to be able to use the checkboxes in front of each category listing on the Categories page and then have an "assign to" option in the bulk options then select the new Category from a drop list. It would have taken me 30 minutes instead of 8+ hours to do what I am doing.