The NY Times has a great article on some of the early adopters of LED lighting, from Buckingham Palace to San Francisco. It's worth reading the whole article, here, which covers pros (cost of operation), cons (narrow light area), and estimated payback period with enough technical detail to elevate it above your usual fluff piece. Most interesting is the idea that conversion to LEDs would allow us to think of light fixtures (bulbs included) more like plumbing fixtures, where you install them once and don't think about them again for years.
On the local side, there are several LED street light experiments underway. You can check them out in person. There are a few demo units in front of PG&E on Beale, an elaborate (if dryly reported) lamp-off in the avenues to test drive different LED manufacturers, and a well-publicized effort to put smart LEDs in the Tenderloin.
Image from PG&E (Photo by Jon Manzo)