After a somewhat heated discussion, we seem to be approaching agreement on how to implement END{} blocks for PL/Perl. They will be done via callbacks registered using the on_proc_exit call. One significant use for this is to make PL/Perl profiling via Devel::NYTProf much less cumbersome.
The accompanying on_perl_init setting feature is still causing some angst, but there seems to be a bit of light at the end of the tunnel. I'm hopeful we can get some progress here without causing too much distaste.
I think the discussion has been instructive - when it has focused more on getting a way forward than on negativity it has been much more productive. There is often a tendency in our community to say "no". I am as bad about it as anybody. But it's worth remembering that people ask for things for a reason, and if we are going to say "no" or be skeptical, we need to make sure that we are still trying to address their needs.