PollyBrit, I'll paste the email from my
travel agent here for you. I interpreted the note to indicate it was a ticketed event for crowd control -- not that there was a fee (but no fee would be very un-Disney-like!

). Anyway, here's the note:
Good Afternoon!
Beginning on Monday, June 6, 2016, you will now have the ability to pre-book meet & greet opportunities with Disney Characters through your My Cruise Plans section of disneycruise.com at the same time you are able to complete your Online Check In!
Sailings 7-nights or longer that feature at least two sea days, will also feature the opportunity for guests to pre-book online a special character breakfast.
Similar to Port Adventures, Guests who have not pre-booked experiences prior to sailing may check availability once onboard.
Guests interested in pre-reserving tickets for the Princess Gathering, Frozen Meet & Greet or Disney Character Breakfast during their cruise vacation, can visit the My Cruise Plans section of www.disneycruise.com on or after Monday, June 6, 2016, to pre-book these experiences.
Please don't hesitate to let me know if you have any questions at all.
Until then...
Have a Disney Day!
Hope that helps!