The arrows are:
Move to Top, Move Up, Move Down, Move to Bottom.
It allows you to change the order they are scheduled.
It might be nice if we at least had a legend or hover text that said what they were.
Glad you noticed the new feature though. You can now bulk list and set up campaigns of 100 items at a time. Of course you can do more by just creating seperate campaigns. It was easiest for us to do 100 since we can fit 100 on a page. In the future we may support groups of more than 100 at a time and seperations of less than 1 minute.