John Carmack, co-founder of id, the creators of Doom, was recently interviewed by website Industry Gamers. The dude is definitely qualified to speak on the matter as he's been a developer for several years, and has done work on various platforms: PC, console and mobile.
He notes that in the time since id started development on Rage, the iPhone has been released and the technology in such devices is quickly catching up to consoles, saying, "That‚Äö√Ñ√¥s one of the things that we do discuss internally a lot and it‚Äö√Ñ√¥s amazing to think that when we started Rage, iOS didn‚Äö√Ñ√¥t exist. There was no iPhone. All of that has happened just in the space of one project development timeline. And that‚Äö√Ñ√¥s a little scary when you think about it, because major landscape change could be happening underneath our feet as we work on these large scale projects."
He added that many developers enjoy the smaller experiences that come with mobile devices. They no longer have to set up in front of a TV. They simply wake their iPad and go. He notes that the iPad 2 is still "a factor of a couple weaker" than the 360, but notes that the speed at which the technology is evolving could mean a tablet more powerful as the PlayStation 3 or Xbox 360 in the next two years "But the fact that it‚Äö√Ñ√¥s gotten that close that fast – that means that almost certainly, 2 years from now, there will be mobile devices more powerful than what we‚Äö√Ñ√¥re doing all these fabulous games on right now," says Carmack.
That's pretty crazy to think. Still, games like Rage and some of the Unreal-powered stuff shows that mobile devices are quickly catching up.