For example, Chris Malone and Ben Jai offered a talk, "Insights Into Google's PUE", that, starting on slide 8, describes how Google uses single volt power and on-board uninterruptible power supply to raise efficiency at the motherboard from the norm of 65-85% to 99.99%. There is a picture of the board on slide 17.
Amazon's James Hamilton attended the conference and elaborated on this:
The server design Google showed was clearly a previous generation ... a 2005 board ... [but] was a very nice design.Also fun is a video tour of one of Google's data centers. The video is short and worth watching for a look at how cooling and wiring is done these days as well as checking out how they used servers in shipping containers.
The board is a 12volt only design ... 12V only supplies are simpler, distributing on-board the single voltage is simpler and more efficient, and distribution losses are lower.
The most innovative aspect of the board design is the use of a distributed UPS. Each board has a 12V VRLA battery that can keep the server running for 2 to 3 minutes during power failures. This is plenty of time to ride through the vast majority of power failures ... [and] it avoids the expensive [and less efficient] central UPS system.
The server was designed to be rapidly serviced with the power supply, disk drives, and battery all being Velcro attached and easy to change quickly.
For more details, Amazon's James Hamilton has additional notes (  ) and CNet's Stephen Shankland links to all the videos (including video of the talks at the summit).