As expected, Google have released v5 of their Google Earth product, which includes 3d seafloor data.

The 3d seafloor data looks pretty neat, although there are a lot of survey artifacts. For example, I looked as the US section of the Gulf Of Mexico continental shelf - lots of canyons and terrain differential, but the grids used by the survey ships are visible as artifacts with a roughly km spacing.  I also saw the same in the Porcupine Basin west of Ireland.

Despite this, it looks pretty neat, and I expect we shall see a lot of "fly through" movies of the more detailed and spectacular areas.

Download and a brief product tour can be found at:  http://earth.google.com/tour.html

Google also have a publicity video on YouTube.