I have to amend the statement above as I just spoke to the person who runs that submersible, a Mr Rob McCallum.
The rumor that Richard Branson and Kate Winslet were going down inb that submersible was not ture - they have not booked it, and the submersible is not even scheduled to be there.
This story was published just last month:
Kate Winslet, Richard Branson to visit Titanic wreck in 2012 - Celebrity News - Digital Spy
But Rob is the guy who has taken director James Cameron down to the Titanic every time says "Well, I read the story, too, but they never called me."