Apple’s latest smartphone, the iPhone 4S, is arguably the year’s hottest handset. Not only did the company sell 4 million units during the device’s opening weekend, but the smartphone is still flying off of retailer’s shelves a month later.

The handset is so popular, in fact, that carriers are having trouble keeping up with consumer demand — Apple can’t make them quick enough. And the phone hasn’t even found its way into mainland China yet, but it’s getting closer…

Sina, a Chinese tech publication, is reporting that the iPhone 4S has just been approved by China’s Ministry of Industry and Information Technology. MIIT is a state agency in China that oversees the regulation and development of the internet and wireless networks.

This is kind of a big deal because it means that Apple’s new smartphone is getting closer to launching in mainland China. Although the handset is already available in Hong Kong, major carriers like China Unicom and China Mobile have yet to offer the device.

The word on the street is that China Mobile and Apple haven’t finalized a deal just yet, but China Unicom is said to be chomping at the bit to carry the phone. The two carriers combine for nearly a billion subscribers, so, needless to say, they’re very important.

After a disappointing third quarter, Apple told investors that they expect $37 billion dollars in revenue in Q4. Getting the iPhone 4S going in China would certainly help with that, but it would also add to the handset’s growing supply problems.

[M.I.C Gadget]