What is the status of Objective-C++ support in mainline GCC? Ziemowit Laski was
working on integrating such support late last year, but has Apple since halted
such integration efforts?
I don't believe anyone is working on it at the moment. It exists, you just have to grab from the apple-local-200502-branch if you want it.
If you'd like to work on it, let us know, we'd be happy to have the help.