Update: Previously, I mentioned that Babel Rising 3D contains in-app purchasing options. These have since been removed.
It is the conventional wisdom of our time that smartphone and tablet gaming are "the future." Like plastics. It's inevitable, it's going to happen - more and more people will move away from the PSPs, the PCs, and the Xboxes to their all-in-one portable devices. Now, that's not to say these other industries are going away any time soon - console and PC gaming will likely to continue to stand on their own for decades (maybe not so much portable consoles).