Tools are important, so I'd recommend to at least mention something about
- Makefiles and how the build process works
- gdb
- lint
- the usefulness of compiler warnings
Concerning C, I think it's important to stress that the programmer should know what "undefined behaviour" really means, i.e. to know that there could be a future problem even if it seems to work with the current compiler/platform combination.
Edit: I forgot: teach them how to search and ask proper questions on SO!
