Watch this video, quite interesting, Secondlife and Social Networks' approach by text100, a PR company represented in 29 countries. Of course it is a bit commercial, but they do share their experiences and thoughts about the future. text100 believe that the power of loyalty in Online Communities will dominates brand building and reputation. Companies need to experiment Virtual Worlds/Social Networks, become early adopter and start building loyalty now. If they don't, a competitor will and a competitor with the best loyalty in social networks within the next 5 years will win the brand building and brand loyalty battle.
Text 100: Branding building in Second Life - ~10 minutes
Now, have a look at this real life project, Patient Opinion, funded jointly by the Department of Health and South Yorkshire Strategic Health Authority.
A revolutionary online system which allows anyone to share their experiences of receiving specialist treatment on the NHS Health Service.
More about Brand loyalty on Word of Mouth Basic Training: How-To: Earn Brand Loyalty in Social Networks?
More about Social Networks on Wikipedia: