I've talked with a lawyer and you can establish a business and then run other businesses under this umbrella company to avoid liability. That's my understanding -- but this isn't legal advice. It makes sense if you have a product that isn't as polished as it should be (experiment) and it causes loss or damage to your users. Of course most people are fucking around with twitter api's and mashups and whatever is hot these days, so I think that is where the author is coming from.