This piece of news was just in minutes ago. According to a China software company call Meuu (me + you), it is currently working with Valve to port Dota 2 over to iOS and Android devices. The portable version for Dota 2 is currently undergoing development, with the engine being used to be Meuu’s own MoSource.
In Meuu’s official company Sina microblog, the most popular social media outlet in China, Dota 2 portable will support single player, Bluetooth and Wifi modes. The Android version reportedly will be the marquee game for Nvidia’s Tegra Zone (link). The microblog post also stated Valve’s “Eric” deing the one who told industry insiders about the news.
After a check, there is no business guy in Valve named “Eric”, but it should be pointing to Erik Johnson, one of Valve’s business development authorities (link). Seen below is a supposed photo of Dota 2 being tested on a tablet and the game’s app logo is beside Steam’s. Do note that this is just a rumor, and take it with a pinch of salt.