These brands came in 2007 the likes of Reuters, BMW, Sony BMG and Ericcson, BigPond, Reebok, Vodafone, IBM, ABC TV, Showtime, Pontiac, American Apparel, Virgin, Dell, NBC, Apple (unofficial), Sears, Circuit City and AOL. (see source)
So why did the came:
It is cool to see your branded store in 3D. You can allow your users to interact with your products in new ways. They can talk about your products in new ways. Users can bring their friends and talk about the products; users can test the products; they can even design a product and feel the service.
So why did they go away:
Well, most of these firms are no longer in Second Life (or no longer in a meaningful way). Reasons include: a lot of work to have a maximum of 40 avatars. A simple web site can deal with 400,000 users. Difficulties to turn visitors into sales. Difficulties to connect second life into web and real commerce systems.
Yet... I want to remind people that it was probably difficult and not very productive to build the first web site of Amazon. It takes time. Virtual Worlds as a medium need to mature. We should not expect to gain "internet" value with the current level of maturity.
For a good example I would look at http://www.orange-island.com/. This firm seems to take it slow, learn the topic, experiment.