I think she is being refit in March of 2008. When you look at the deck plans, they have two different sets - before March 16, 2008 and after March 29, 2008.
Will you be sailing on the March 15th cruise to Hawaii in 2009? That's the one I've booked.
Mercury was just done in April of this year. Below is a link to what was done. There has been no announcement from Celebrity as to any other changes at this point, only rumors. Even so, next year Galaxy is being done and they are not putting a specialty restaurant on her so don't expect any on the Mercury. Anything you here now is only rumor and Celebrity's rumor mill has never been too accurate.