Blizzard Entertainment is bringing microtransactions to Diablo III in select regions via an upcoming patch that will add (among other things) timed experience boosts, cosmetic items and a new "Platinum" in-game currency that can be purchased for real money.
By layering in a "premium" currency between players and in-game items, Blizzard is using a premier F2P monetization trick that's a significant departure from the design of Diablo III's defunct Auction House.
In posts on both the European and North American Diablo III forums, Blizzard employees break down the upcoming Patch 2.2.0 and take pains to point out that the company will not be adding these microtransaction opportunities to the game in either region -- yet.
That suggests that Blizzard will roll out the microtransaction system to Diablo III players in Asia, specifically China -- where microtransactions are considered de rigueur in online games and Blizzard partner NetEase operates a version of Diablo III modified to be more palatable to Chinese players.