Warcraft IV probably isn't going to be coming along for a very, very long time. Blizzard's got a lot on its plate, after all, and as far as the Warcraft franchise is concerned, World of Warcraft's pretty much got things locked down. StevenLuo of the Team Liquid forums wasn't so content with this state of affairs. He decided he wanted to take matters into his own hands.
Using the Starcraft 2 Map Editor and a bunch of assets pulled straight from World of Warcraft, he's managed to create an entire game. Though there's not any sort of single-player campaign mode (not yet, at any rate), he's implemented two full factions(Alliance and Horde), complete with models, textures, and sounds. Currently, there are three playable melee maps, fourteen buildings, sixteen units, eighteen heroes and over fifty creeps. Altogether, the whole package takes up around 245 MB of space.
The game features a number of units and assets pulled directly from World of Warcraft, including Undead Rogues, Blood Elf Paladins, and a whole range of Pandaren special units, as well.
Currently, the three melee maps all draw heavily from World of Warcraft: Lost Temple is modeled after several different Blood Elf areas, while Crossroads and Ashendale are actually modeled after the in-game zones of the same name. The mod also features the ability to easily create and add new maps to the framework, allowing the game to be expanded by the community as they see fit. Each map is about 5 MB in size.
According to Luo, the original idea for his mod - which he refers to as "WAH" - came ten years ago, back when World of Warcraft was first in Beta. Luo, who didn't have an account, was forced to sit and watch others play the game. Not content with doing so, he decided to use the Warcraft III editor to create his own World of Warcraft, which he worked on for about three months before the project fell off.
Upon realizing his desire to play another Warcraft game - and the extremely low chances of that happening - Luo decided to put his eight years of coding experience to work using the Starcraft II Editor. The current version represents approximately eight months of work; after six months working on it in his free time, Luo quit his job in order to focus seriously on the project. Two months later, he completed version 1.0.
At a later date, Luo intends to implement the Burning Legion - basically, demons - as a playable race. For the moment, he's focusing on bug-fixes, balance issues, and performance improvements. He's put a call out to the community to give him suggestions for how he is to proceed with the mod, and improvements that he can make.
From where I stand, this guy's exactly the sort of innovative, creative mind a game studio should be looking for. So, to Blizzard, I say: what are you guys waiting for? Give this man a job!
To everyone else: go here for instructions on how to play.