Companies seem to find Second Life compelling too. Apart from the marketing value of wading into the pool first, this makes little sense (and probably makes no money). The current 3D interface is horribly inefficient for e-commerce and needlessly taxing for computers. It's simply an unnecessary conceit. The whole point of shopping at Amazon.com is so I don't have walk anywhere, virtually or otherwise.
Businesses want a controlled environment to interact with customers and potential customers, which completely obviates the need for a massively multiplayer world full of unruly people.
Companies interested in virtual interaction would be much better off with something like Unisfair Live Online Expo, which is essentially Sim Trade Show.
I'll concede Second Life is interesting in terms of the legal issues it raises and as an example of the appeal of user-generated content. Of course the same can be said of drug smuggling. In any event, it would make a great development platform for a World of Warcraft-style game.