I use Thames Clippers every day to take the boat from St katherines to Canary Wharf and sometimes beyond that. It's probably one of the most civilised ways to travel to and from work ever! Irregular, and not as cheap as the tube, but hey, what a way to travel!
I don't have any connection to the owners but I did go to a presentation by AEG (the company)recently about the Dome (or the "02" as they are trying to call it!). Although a casino is part of their plans they are also building a huge range of other things including a massive concert venue, a cinema and shops and restaurants and most of that is going to open next year regardless of the casino issue. So they are going to need to get thousands of people in and out some way other than just the Jubilee Line and the river seems quite a good idea to me. pretty good option for the olympic stuff that's going to be there too.