Think about it though... this is a game that is ALLOWING you to play mindless hours to earn money. Like lets say you grind/grind/grind and you get to level cap. Guess what? There are tons of other people who will do the same thing.
I've thought about it a little... and lets say it takes you 45 mins to hour and a half to get X rare item. You can now sell that rare item for $5. Let's break it down:
A. You had fun playing through the instance or dungeon to get X item.
B. You don't need X item because your class doesn't require you to have it.
C. You sell the item on the cash shop and make $4 (or whatever Blizz will tax).
D. You can also undercut gold farmers severely and enjoy your well earned money (and essentially play the game to pay for itself).
I mean, I totally understand that this will ruin the game for some... but remember... Diablo isn't an MMO. So it won't affect you directly in terms of balance in the single player portion of the game. It will however be sorta weird to have people using their real money to get awesome loot just so they can PvP well (once at level cap anyways).
So now that I've thought about it, I won't be sour when I buy the game. I'll only think to make a quick buck or two by playing a game I like. 
Oh i have thought about it long and hard... at first i was happy about it thinking the same thing, i will have fun playing a game and make some money while i am at it... but the reality bit me in the ass
a. nope, i was mindlessly farming and doing a job with little or no pay, not for fun but to get money, i don't call farming for money fun...
b. even if I find an item i need i will think if i should sell it and make money and buy a few beers with it ... i will never give an item to a friend if can sell it to, witch sux for me and them
c. if you can sell it, if not you only give money to blizz
d. no way in hell will this be worth it... they will undercut you, they don't care if they make 5 cent per item because they sell tons of them, there are thousands of them, you are one
and to people saying "you dont have to use it" ... true i don't but i will, because of greed and even i i don't it still affects me because it affects the whole economy...
pvp has no more meaning anymore, no way to stay competitive unless you buy you gear
this has to be the worst thing they could have gone with... if the wanted money i would have rather payed 5$ a month or they could sell stuff like dyes / pets / hats / whatever ... something that doesn't have any meaning except for looks
and yeah now even more people will try to hack the game then ever because it will be worth it... there will be more private bots / dupes / exploits then in any other game... witch sux big time, blizzard should just start selling those "because they can't stop them" ... just as they can't stop this... stupid stupid solution if you can call it that
You're talking about Blizzard dude. Do you honestly think they're going to allow D3 to be like D2 with hacks and dubs? Has anyone played the beginning of Burning Crusade in WoW? There were several hacks that made crazy-powerful items with five digit numbers across the stats on a shoulder piece. In less than 24 hours, the dudes that hacked the item were banned and all related items were removed from the game. So quit worrying about shit like that.
I can tell most of you will be playing regular mode, so you'll have to deal with the real money issues. Since it's region locked, AH will be on a single server per region. So you're going to have tons of shit on AH.
D3 Game Mechanics - Should really check this system out. This is an interesting read I found:
Resource SystemsInstead of every class using Mana, like in the previous two Diablo titles, Diablo III has been confirmed to utilize 5 different resource types, giving each class a unique playstyle:
The Barbarian gains Fury by attacking his opponents and by taking damage. After the Barbarian uses an ability, Fury is drained by a fixed amount. Careful combinations of abilities are critical for the Barbarian to maintain his devastating attacks: the player must choose which abilities to use on which opponents.
The Witch Doctor is the only class to not have it's resource system modified, thus it's resource has remained as Mana. The Witch Doctor starts off with a full amount of Mana, and a fixed amount is drained depending on the skill used. The Witch Doctor will have several ways to regain Mana, including the use of skills such as Soul Harvest and Mind and Body, Traits like Spirit Vessel and Mana Regeneration, or by equipping class-dependent items.
The Wizard will use Arcane Power. This system is similar to Mana in that it begins full and is drained as abilities are used. However, Arcane Power will be expended and replenished far more quickly than Mana.
The energy source for the Monk is Spirit. The system relies on a balance of combo and non-combo moves. Combo moves will build up his Spirit, which he will then use to activate his finishers.
The Demon Hunter uses a dichotomous resource system of Hatred and Discipline (the actual name of the resource system is currently unknown). Hatred will be used for bow attacks and burst damage, while Discipline will be used in trap-setting and other preparatory maneuvers. Of the two, Hatred will be the more commonly used resource.[2]
