This week the American Society for Heating, Refrigerating and Air-conditioning Engineers (ASHRAE) adjusted their recommended upper limit for ambient data center temperatures from 77 degrees to 80.6 degrees. Combining this with reports from Google, Intel, Sun, and HP, you can easily see that servers do not mind "higher" temperatures as much as you would think.
I have to address this many times on tours, as we keep our facility at ~72 degrees Fahrenheit for the inlet temperatures on servers. It seems many people expect the facility to be significantly cooler, say in the 64-66 degree range. As these reports show, keeping a data center at those levels is simply not necessary as it does not prove to have any benefit for reliability, performance, etc. The only real difference is that keeping a facility at those temperatures simply costs a lot more and wastes more energy. It is true, that at warmer temperatures you need to be more wary of hot spots, but with regular monitoring and a properly engineered facility, that should not become an issue.
As a note, our facility even easily met the old ASHRAE standards. You can see in this graph/report that our spec of 72 degrees Fahrenheit and 45% relative humidity are solidly in the area recommended for a Class 1 Operating Environment.