Firstly, there is Heroes of Newerth, a total conversion running on its own engine and selling for the retail price of 30$. There is an info page about the differences to DotA Allstars.

Also, League of Legends is already out, done with the help of some of the former DotA developers. But this one is free to play. I have tried it out and it is fun to play, though it seems very resource costing considering the `unpolished' graphics it is presented in.

And then there is Bloodline Champions which currently is in an alpha stage, but looks promising. It differs from the other two games as the hero is moved via the `wasd' keys and the mouse targets the hero's attack. There seem to be no creeps in the game and it kinda reminds me of the multiplayer mode of the infamous Nox. Also, mana has been removed and spells and abilities only rely on a cooldown to function.