Spirit Airlines becomes the first airline in the world to charge for carry-on baggage. In an ongoing effort to reduce ticket prices and allow passengers to choose what services they want to pay for, customers who fly on or after August 1st will have to pay a fee for carry-on baggage that goes into the overhead bins. Bags that fit under the seat will remain free (I have one question, what happens to someone in a bulkhead row with no seats in front of them?) At the same time Spirit has reduced the fee required for checked baggage. For full details please see this press release from Spirit.
Here is a nice graphic from Spirit showing the fee breakdown