"In Europe, there have been successes and failures. If we just focus on one success, we may see a hint of what the future will bring. BSkyB in the UK has "given" to their subscribers hundreds of thousands of STBs to receiver a DTV signal (at this point we will not differentiate between satellite and terrestrial). Their model works: sports and movies. In the meanwhile, Free-to-View, in the UK is working too. BSkyB after enormous expenditure will have huge operating profits this year. Is the picture clearer?" quoted from bbrv.
This summary as stated is correct, but does need qualification. BSkyB's sucess has been built on programme content, not on method of delivery. As Bill says it has been built on a huge investment, largely to gain exclusive coverage of sports, the jewel in the crown being English Premier football. The point here is that other companies moving into this market may find it difficult to compete in the UK without comperable incentives to viewers.
The passing reference to Free-to-View is a bit misleading. This service started life as OnDigital which then became ITV Digital. This service collapsed with large debts, due to trying to emulate BSkyB with an over costly football deal with the English Football league. It was rescued by a combination of BSkyB (remember them) and the BBC and is therefore supported (unfairly some might say) by the licence fee.
In the UK the set-top boom has been often reported, but never really happened (as yet).