I have looked at it, but I'm not convinced.
C++ is out of the question - I don't like it, and it's just too much work trying to make a conforming compiler. As I have said before, adding "half" a language is useless - either you make a full implementation or you don't do it at all.
That said, there seem to be several "C with classes" available - not only Objective C. None of them seems bigger or better than anyone else. None of them are "standard", which also makes them pretty useless (to me at least).
One common approach is to use a "preprocessor" that emits C code, which can be compiled using a normal C compiler. This approach should work for, say, Objective C too - but I'm reasonably sure the preprocessor shouldn't be part of the Pelles C distribution.
Pelle