>>7
There is always a catch. MS wouldn't just allow free OS downloads. Its either
1.Crippled, feature poor demo with most of functionality reserved for release.(unlikely)
2.Time limited demo. It will stop working after W8 retail sales start.(more likely)
3.MS will try to push App Store as main revenue model with basic OS for free.(slight chance)
4.It contains some phone-home checkup routine which will allow 2.(likely) or something akin to spyware/adware(unlikely)