Path of Exile free to play in about six hours.

[LennyLen]

So is it now possible to make real money by selling stuff to other people in this game?

There is no RMAH, and GGG have stated that there never will be.

There is nothing stopping two individuals from making an agreement outside of the game though, and the official stance on this is that policing such activity would be impossible and that GGG in no way support it. If you agree to pay someone for an item you do so at your own risk and if they take your money and don't give you the item, it's your own fault.