Wow...All these people saying they hope that Valve loses. Do you realize what reselling games would do to the market, and in return to Valve, and in return to us..the consumers? Nope, because most people's understanding of business on this forum is beyond lacking.
Let us take a look at the scenario where they would allow us to resell our used games.
There is a Market button on steam, that allows you to buy used games at a cheaper price. There is a quantity of those games being sold. Lets say it is 40% cheaper than the original price. We of course will buy the used games, rather than the new ones. The company that made the game, now gets no money, Valve, now gets no money from sales of the new games, and in return this will Lead to developers who already hate PC gamers, develop even less, due to lower revenue returns and quantity of games sold. Valve in return won't be able to afford to give us the Sale prices that we get right now, which let's be honest, a lot of you LOVE buying games for 1-10$ each, which you could not do with a console game even if it was used. In the end, the developers would either do even LESS for PC gamers, which they have every right to do if they get no money from used games, than they will take their business elsewhere, OR the developers will increase the prices of the games, and Valve will stop doing it's sale prices, which lets be honest is probably more than half of your steam Library comes from Sale Prices. Either way the consumer will hurt more in the end.
There is a way around it so that Valve still makes some money back, as well as the company that made the game, by let's say, getting 20% of the sold Used game's price. So lets say you sell a game for 10$, you get 8, and the rest goes to Valve/Developers. But, if this is the case, I still think they would stop doing their sales, since than there would be a problem of what is the right price for X used video game, do I sell it at a discount of the original, or do I sell it at a discount of the Discounted price I bought it at? Ect ect. Honestly there is little you can do, to make it so that the consumer is happy in this situation.
That is just my