Putting Thoughts Together
Something that I have said a number of times is that nowadays, there is almost no reason to pick C over C++ for a new project (one of the few reasons that I know of involve writing execute-in-place code for very small embedded systems, so no, GNOME definitely doesn't qualify!). Worst case, you write exactly the same code you'd have written in C, just avoiding using the new keywords as identifiers, and you then get better warnings (remember, no templates would be involved) and stricter type checking (no more silent casting of void* to pointers to random things! No more setting enums from any random integral junk you happen to have at hand! No more forgetting a header and using a function with the wrong parameters!).
But these slides really put it together, from someone who's generally thought of as neither insane or dumb. Doesn't really have much to do with GCC in particular, other than just the general fact that this is becoming so obvious that even GCC might be making the switch...
Edit: This article by Amit Patel is also pretty good on this subject.