334 Personal Content Experience: Managing Digital Life in the Mobile Age Metadata may be playing a crucial role in targeted advertising. It enables marketing on the basis of metadata entries, much as Google is currently doing with their AdWords, but using content metadata instead of web pages as the source. For instance, listening to Schbert’s latest song on your MP3 player suggests that you might be interested in the ads by a clothing store he endorses. As discussed in section 7.4., some online communities are more than virtual. This is the case with the online game Second Life, where 6 virtual assets are purchased with real money. It is worth noticing that even some (real) artists have started streaming “live” concerts in this 7 virtual world. At the same time, virtual characters for the popular multiplayer game World of Warcraft are being offered in online auctions for bids in real money. One eBay seller listed “Three level 60 characters (Warlock, Priest, Hunter)” for bidding, justifying the $190 price with “This levelling up three characters took me like more than 80–90 days. I want to sell this off for a cheap and reasonable price.” The potential of virtual economy may far surpass our expectations. 8.4 Obstacles in Reaching the Vision Making a vision become reality requires a lot of research and develop- ment. What it also includes is overcoming a number of problems, threats, and obstacles along the way, be they technical, psychological, economical, physical, social, etc. In this section, we analyse some of the most probable issues along the way towards the vision. We divide the treatment into two categories: technology-originated issues, and human-related. 8.4.1 Technical Problems and Challenges Most of the identifi ed problems can be, not surprisingly, derived from the vision topics and technical enablers discussed above. For instance, the community-created ontologies, or any other ontologies, provide a good foundation for more generic ontologies. However, how far should we go? Should the whole world be modelled, and to what extent and granularity level? Such a task is close to impossible, not to speak of 6 “The average going rate for land parcels in Second Life is between $100 and $1,000.” Quoted from: “Second Life realtor makes $1 million” in http://www.gamespot.com/ news/6162315.html 7 http://www.wired.com/news/technology/internet/0,71593-0.html?tw=rss.index