In a recent blog made by Pendragon, the owner of www.DotA-AllStars.com, he announced the shutting of the site due its inactivity as well as his lack of time.
For a few days, there have been rumours saying that IceFrog worked in the development of Heroes of Newerth and it seems that Pendragon confirms these rumours.
Here is an extract of his blog post regarding IceFrog and S2Games.
"While I originally intended to leave this out of this letter, in light of the fact that this information is now out in the open, I think it�s important to set the record straight. Many believe that Icefrog left because I wanted to commercialize, and he did not. In reality � I had learned that Icefrog had been secretly working for S2Games after conducting a series of meetings where he was attempting to sell a full DotA game concept to a number of companies (including Riot). The differences of opinion that we had were merely that I chose to be transparent and honest about the project that I was working on, and the direction my career was going."
Source: DotA-AllStars