My fedora12 installed a tool called ABRT that comes probably with GNOME. This tool operates at the background and reports at realtime any process that has crashed.
I have used a signal handler that was able to catch a SIGSEGV signal, ie it could report crashed.
What other ways exist in order a process to get information about the state (especially a core) of an other process without having parent-child connection?
Any ideas? It seems a very interesting issue.
ABRT is open source, after all, so why not look at their code. The architecture is explained here -- it looks like they monitor $COREDUMPDIR to detect when a new core file appears.