My post about the environmental value of white roofs garnered quite a bit of attention back in early 2004. According to research done at the Lawrence Berkeley National Laboratory, in warm weather regions, using white rooftops -- tiles, paint or other -- had a substantial environmental benefit, potentially greater than would be gained using traditional solar panels. It's good to see the idea is still getting some play -- as with this post in Treehugger today, quoting from a recent issue of New Scientist (which also mentions GRUMP -- the Global Rural Urban Mapping Project, which we talked about in March of this year).
If you live in a warmer area, as a growing number of us do, installing a white roof can be one of the smartest things you can do to both keep your power bills down and improve the local "urban heat island" effect. Other good steps: planting more trees and getting local city planners to avoid using dark black road seal.