The largest mobile handset maker, Nokia, just announced their own set of dual SIM handsets. It's only a matter of time before smart phones have this feature as well. Yet another example of innovation driven by knockoff artists!
... Why is Nokia doing this now? In part, I think, it's because it doesn't want to be out-innovated by pirates. But it's also because Chinese vendors that start out producing knock-offs quickly learn the ropes and then start to produce increasingly competitive products. We've seen this happen with network gear and cars in the past decade, and now it's starting to happen with phones