The barge floating in the San Francisco Bay that was discussed last week is likely a mobile showroom with a party deck. This way, the facility can be taken anywhere around the world (by land or by sea) and show the company's wares.

Google won patents for water-based data centers in 2009.

Advantages include inexpensive and efficient cooling, using seawater. The cooling is one of the biggest expenses of a datacenter. It’s theoretically possible to power it by generating electricity from wave motion. Google owns a world-spanning fibre-optic cable.

Is Google building a hulking floating data center in SF Bay? from CNET

Is Google building a floating datacenter? From Springfield News Sun

Patent: Water-based data center

Report: Google barge not a data center from Data Center Dynamics