According to a Sun press release, they've completed the largest datacenter consolidation project in the company's history -- which they expect to save $1M in electricity costs, and 11,000 metric tons of CO2 per year. More details in the linked article, but the datacenter uses flywheel-based UPSes, a high-end Liebert XD cooling system that can dynamically allocate the amount of cooling based on demand. (Note the little air hoods over each rack.)
The major focus seems to be on space and cooling efficiency, estimating a PUE of about 1.38. (For every 1 W of computing power, 1.38 W of power enters the datacenter.) For interesting comparison, Google claims a PUE of 1.21 across six datacenters, with one running at 1.13. It's quite likely that some of those datacenters use evaporative cooling in friendly environments, etc.