Pretty much every laptop computer you buy today is already made in China. That Macbook Pro that the paranoid executive won't take to China? Made in China.
There are some reasons to suspect corporate espionage, but the nationality of the perpetrator is irrelevant. I'm unclear about the exact motivations for the rampant China bashing that seems to happen in our media today, but the Chinese as a people have every motivation to not engage in dishonest dealing -- they need the West's money in order to continue modernizing their economy. China was a third world nation only 20 years ago, with an industrial base similar to that of most Western nations in the 1950's but 10 times more people to support with that industrial base. They've come a long ways in the past twenty years, but still have a lot further to go and they know it. Engaging in organized skulduggery (as vs. the ordinary disorganized industrial espionage that happens between business competitors) is not in their best interests and the least of our worries.
I've managed Chinese programmers working on security products. They're smart, but green. They still have a lot to learn about what it takes to get products through the whole product cycle from concept to final delivered product in the customer's hands, and they know it. Perhaps at some time in the future we'll need to worry about Chinese programmers inserting time bombs into security products, but today? Again, they have too much to lose, especially if their code is being regularly reviewed by senior American engineers, as was true in our case.
In short, you should definitely follow your normal procedures for detecting and closing security vulnerabilities, but singling out one nation -- China -- for special scrutiny is just plain silly. Yes, follow good practices -- don't leave your cell phone out and about, same deal with your laptop computer, make sure your firewall software is running, don't stick foreign media into your computer's ports or hard drives or install unsigned programs, if you've outsourced development have regular design and code reviews to catch security issues early, etc. But I have to think that all this emphasis upon one nation as a "threat" has more to do with politics than with technology, and distracts us from the real problems of securing our computers against real threats -- which are more likely to come from Eastern European virus writers than anything coming out of China.