Is there any reason to ask this? GCC plugins have been good since 4.8. 4.5 lacked some essential features; 4.6 would be fine if not for the annoyance of trying to support a plugin that works across the C++ transition. Of course, you can just use the Python plugin to save yourself a lot of sanity ...

They work. You can use them? They haven't gone anywhere and the Linux kernel relies on them extensively, among other things.