Game Developer Research's annual "State of Game Development Survey" revealed that the PC and Mac are the most popular game development platforms. Surprising, no? Actually, it's not when you consider that social games (i.e. Facebook games) and browser games were lumped into the mix. As for consoles, the Xbox 360 still leads the way.
On the handheld front, developers are flocking to the iPhone and iPod Touch platform, leaving the Nintendo DS and Sony PlayStation Portable in the dust. It's not surprising really. Facebook, browser, and iPhone games are cheaper to make than traditional console games. The market is relatively new and the players are still being established. There are more opportunities in these markets for new(er) developers and publishers.