Having been on the hiring side of this, I'll note that it does require a bit of start-up cost (i.e. work) on the employer's part, if you want to standardize the process (i.e. to make sure you're giving the same exercise to every candidate, the expectations are clear and consistent, etc).
For example, I set up the project for my team in 7 different languages (Ruby, C, Python, Perl, C++, Java, Go), with the appropriate project structure, etc, for each. This took considerable work on my part, but the end result is that I can judge the output based on whatever the candidate is most comfortable in.
Granted, that's all assuming my skills in each language doesn't completely suck (hopefully).
For example, I set up the project for my team in 7 different languages (Ruby, C, Python, Perl, C++, Java, Go), with the appropriate project structure, etc, for each. This took considerable work on my part, but the end result is that I can judge the output based on whatever the candidate is most comfortable in.
Granted, that's all assuming my skills in each language doesn't completely suck (hopefully).