I suppose Crysis and UT3 would be good examples of this, I have seen a *lot* of people on the net saying they would like to play games like these but their machines simply aren't up to it, which often leads on to conspiracy theories that this was a deliberate move by the developers due to Nvidia/Ati/Intel/AMD giving them large sacks of money to make sure the games aren't playable on older hardware, thus boosting sales of their latest products. If the conspiracy theories are true then surely there would have to be a lot of money involved to compensate the developers for the sales they are going to lose.