[khyryk]

Generally, the good reasons you'll see for using C are lack of C++ compiler availability and embedded programming.

The bad reasons tend to be variations of developer inertia and the inability to decide which features of C++ ought to be used -- arguing against the STL isn't a good argument against C++ as a whole.

[netbyte]

On Linux/Mac you have g++ and on Windows you have MinGW/Visual Studio

[khyryk]

There are many more operating systems out there.